diff --git a/cmd/aws/main.go b/cmd/aws/main.go
index fc2ad215..b29e2fb8 100644
--- a/cmd/aws/main.go
+++ b/cmd/aws/main.go
@@ -31,9 +31,9 @@ import (
 	tesseract "github.com/transparency-dev/static-ct"
 	"github.com/transparency-dev/static-ct/storage"
 	"github.com/transparency-dev/static-ct/storage/aws"
-	"github.com/transparency-dev/static-ct/storage/bbolt"
 	tessera "github.com/transparency-dev/trillian-tessera"
 	taws "github.com/transparency-dev/trillian-tessera/storage/aws"
+	aws_as "github.com/transparency-dev/trillian-tessera/storage/aws/antispam"
 	"golang.org/x/mod/sumdb/note"
 	"k8s.io/klog/v2"
 )
@@ -54,13 +54,14 @@ var (
 	origin                     = flag.String("origin", "", "Origin of the log, for checkpoints and the monitoring prefix.")
 	bucket                     = flag.String("bucket", "", "Name of the bucket to store the log in.")
 	dbName                     = flag.String("db_name", "", "AuroraDB name")
+	antispamDBName             = flag.String("antispam_db_name", "", "AuroraDB antispam name")
 	dbHost                     = flag.String("db_host", "", "AuroraDB host")
 	dbPort                     = flag.Int("db_port", 3306, "AuroraDB port")
 	dbUser                     = flag.String("db_user", "", "AuroraDB user")
 	dbPassword                 = flag.String("db_password", "", "AuroraDB password")
 	dbMaxConns                 = flag.Int("db_max_conns", 0, "Maximum connections to the database, defaults to 0, i.e unlimited")
 	dbMaxIdle                  = flag.Int("db_max_idle_conns", 2, "Maximum idle database connections in the connection pool, defaults to 2")
-	dedupPath                  = flag.String("dedup_path", "", "Path to the deduplication database.")
+	inMemoryAntispamCacheSize  = flag.Uint("inmemory_antispam_cache_size", 256<<10, "Maximum number of entries to keep in the in-memory antispam cache.")
 	rootsPemFile               = flag.String("roots_pem_file", "", "Path to the file containing root certificates that are acceptable to the log. The certs are served through get-roots endpoint.")
 	rejectExpired              = flag.Bool("reject_expired", false, "If true then the certificate validity period will be checked against the current time during the validation of submissions. This will cause expired certificates to be rejected.")
 	rejectUnexpired            = flag.Bool("reject_unexpired", false, "If true then CTFE rejects certificates that are either currently valid or not yet valid.")
@@ -147,9 +148,19 @@ func newAWSStorage(ctx context.Context, signer note.Signer) (*storage.CTStorage,
 	if err != nil {
 		return nil, fmt.Errorf("failed to initialize AWS Tessera storage driver: %v", err)
 	}
-	appender, _, _, err := tessera.NewAppender(ctx, driver, tessera.NewAppendOptions().
+
+	var antispam tessera.Antispam
+	if *antispamDBName != "" {
+		antispam, err = aws_as.NewAntispam(ctx, antispamMySQLConfig().FormatDSN(), aws_as.AntispamOpts{})
+		if err != nil {
+			klog.Exitf("Failed to create new AWS antispam storage: %v", err)
+		}
+	}
+
+	appender, _, reader, err := tessera.NewAppender(ctx, driver, tessera.NewAppendOptions().
 		WithCheckpointSigner(signer).
-		WithCTLayout())
+		WithCTLayout().
+		WithAntispam(*inMemoryAntispamCacheSize, antispam))
 	if err != nil {
 		return nil, fmt.Errorf("failed to initialize AWS Tessera storage: %v", err)
 	}
@@ -159,12 +170,7 @@ func newAWSStorage(ctx context.Context, signer note.Signer) (*storage.CTStorage,
 		return nil, fmt.Errorf("failed to initialize AWS issuer storage: %v", err)
 	}
 
-	beDedupStorage, err := bbolt.NewStorage(*dedupPath)
-	if err != nil {
-		return nil, fmt.Errorf("failed to initialize BBolt deduplication database: %v", err)
-	}
-
-	return storage.NewCTStorage(appender, issuerStorage, beDedupStorage)
+	return storage.NewCTStorage(ctx, appender, issuerStorage, reader)
 }
 
 type timestampFlag struct {
@@ -208,7 +214,7 @@ func storageConfigFromFlags() taws.Config {
 	if *dbUser == "" {
 		klog.Exit("--db_user must be set")
 	}
-	// Empty passord isn't an option with AuroraDB MySQL.
+	// Empty password isn't an option with AuroraDB MySQL.
 	if *dbPassword == "" {
 		klog.Exit("--db_password must be set")
 	}
@@ -230,3 +236,32 @@ func storageConfigFromFlags() taws.Config {
 		MaxIdleConns: *dbMaxIdle,
 	}
 }
+
+func antispamMySQLConfig() *mysql.Config {
+	if *antispamDBName == "" {
+		klog.Exit("--antispam_db_name must be set")
+	}
+	if *dbHost == "" {
+		klog.Exit("--db_host must be set")
+	}
+	if *dbPort == 0 {
+		klog.Exit("--db_port must be set")
+	}
+	if *dbUser == "" {
+		klog.Exit("--db_user must be set")
+	}
+	// Empty passord isn't an option with AuroraDB MySQL.
+	if *dbPassword == "" {
+		klog.Exit("--db_password must be set")
+	}
+
+	return &mysql.Config{
+		User:                    *dbUser,
+		Passwd:                  *dbPassword,
+		Net:                     "tcp",
+		Addr:                    fmt.Sprintf("%s:%d", *dbHost, *dbPort),
+		DBName:                  *antispamDBName,
+		AllowCleartextPasswords: true,
+		AllowNativePasswords:    true,
+	}
+}
diff --git a/cmd/gcp/main.go b/cmd/gcp/main.go
index 8dc1c674..f53cb7c2 100644
--- a/cmd/gcp/main.go
+++ b/cmd/gcp/main.go
@@ -33,6 +33,7 @@ import (
 	"github.com/transparency-dev/static-ct/storage/gcp"
 	tessera "github.com/transparency-dev/trillian-tessera"
 	tgcp "github.com/transparency-dev/trillian-tessera/storage/gcp"
+	gcp_as "github.com/transparency-dev/trillian-tessera/storage/gcp/antispam"
 	"golang.org/x/mod/sumdb/note"
 	"k8s.io/klog/v2"
 )
@@ -53,7 +54,8 @@ var (
 	origin                     = flag.String("origin", "", "Origin of the log, for checkpoints and the monitoring prefix.")
 	bucket                     = flag.String("bucket", "", "Name of the bucket to store the log in.")
 	spannerDB                  = flag.String("spanner_db_path", "", "Spanner database path: projects/{projectId}/instances/{instanceId}/databases/{databaseId}.")
-	spannerDedupDB             = flag.String("spanner_dedup_db_path", "", "Spanner deduplication database path: projects/{projectId}/instances/{instanceId}/databases/{databaseId}.")
+	spannerAntispamDB          = flag.String("spanner_antispam_db_path", "", "Spanner antispam deduplication database path projects/{projectId}/instances/{instanceId}/databases/{databaseId}.")
+	inMemoryAntispamCacheSize  = flag.Uint("inmemory_antispam_cache_size", 256<<10, "Maximum number of entries to keep in the in-memory antispam cache.")
 	rootsPemFile               = flag.String("roots_pem_file", "", "Path to the file containing root certificates that are acceptable to the log. The certs are served through get-roots endpoint.")
 	rejectExpired              = flag.Bool("reject_expired", false, "If true then the certificate validity period will be checked against the current time during the validation of submissions. This will cause expired certificates to be rejected.")
 	rejectUnexpired            = flag.Bool("reject_unexpired", false, "If true then CTFE rejects certificates that are either currently valid or not yet valid.")
@@ -157,13 +159,22 @@ func newGCPStorage(ctx context.Context, signer note.Signer) (*storage.CTStorage,
 		return nil, fmt.Errorf("failed to initialize GCP Tessera storage driver: %v", err)
 	}
 
+	var antispam tessera.Antispam
+	if *spannerAntispamDB != "" {
+		antispam, err = gcp_as.NewAntispam(ctx, *spannerAntispamDB, gcp_as.AntispamOpts{})
+		if err != nil {
+			klog.Exitf("Failed to create new GCP antispam storage: %v", err)
+		}
+	}
+
 	opts := tessera.NewAppendOptions().
 		WithCheckpointSigner(signer).
-		WithCTLayout()
+		WithCTLayout().
+		WithAntispam(*inMemoryAntispamCacheSize, antispam)
 
 	// TODO(phbnf): figure out the best way to thread the `shutdown` func NewAppends returns back out to main so we can cleanly close Tessera down
 	// when it's time to exit.
-	appender, _, _, err := tessera.NewAppender(ctx, driver, opts)
+	appender, _, reader, err := tessera.NewAppender(ctx, driver, opts)
 	if err != nil {
 		return nil, fmt.Errorf("failed to initialize GCP Tessera appender: %v", err)
 	}
@@ -173,12 +184,7 @@ func newGCPStorage(ctx context.Context, signer note.Signer) (*storage.CTStorage,
 		return nil, fmt.Errorf("failed to initialize GCP issuer storage: %v", err)
 	}
 
-	beDedupStorage, err := gcp.NewDedupeStorage(ctx, *spannerDedupDB)
-	if err != nil {
-		return nil, fmt.Errorf("failed to initialize GCP Spanner deduplication database: %v", err)
-	}
-
-	return storage.NewCTStorage(appender, issuerStorage, beDedupStorage)
+	return storage.NewCTStorage(ctx, appender, issuerStorage, reader)
 }
 
 type timestampFlag struct {
diff --git a/deployment/live/aws/conformance/ci/.terraform.lock.hcl b/deployment/live/aws/conformance/ci/.terraform.lock.hcl
new file mode 100644
index 00000000..a9e266b5
--- /dev/null
+++ b/deployment/live/aws/conformance/ci/.terraform.lock.hcl
@@ -0,0 +1,66 @@
+# This file is maintained automatically by "terraform init".
+# Manual edits may be lost in future updates.
+
+provider "registry.terraform.io/hashicorp/aws" {
+  version     = "5.92.0"
+  constraints = "5.92.0"
+  hashes = [
+    "h1:ZnpTxMfg5PThZc5WZCsZELinsR0gPhdTpNmXjVcf7aE=",
+    "zh:1d3a0b40831360e8e988aee74a9ff3d69d95cb541c2eae5cb843c64303a091ba",
+    "zh:3d29cbced6c708be2041a708d25c7c0fc22d09e4d0b174360ed113bfae786137",
+    "zh:4341a203cf5820a0ca18bb514ae10a6c113bc6a728fb432acbf817d232e8eff4",
+    "zh:4a49e2d91e4d92b6b93ccbcbdcfa2d67935ce62e33b939656766bb81b3fd9a2c",
+    "zh:54c7189358b37fd895dedbabf84e509c1980a8c404a1ee5b29b06e40497b8655",
+    "zh:5d8bb1ff089c37cb65c83b4647f1981fded993e87d8132915d92d79f29e2fcd8",
+    "zh:618f2eb87cd65b245aefba03991ad714a51ff3b841016ef68e2da2b85d0b2325",
+    "zh:7bce07bc542d0588ca42bac5098dd4f8af715417cd30166b4fb97cedd44ab109",
+    "zh:81419eab2d8810beb114b1ff5cbb592d21edc21b809dc12bb066e4b88fdd184a",
+    "zh:9b12af85486a96aedd8d7984b0ff811a4b42e3d88dad1a3fb4c0b580d04fa425",
+    "zh:9dea39d4748eeeebe2e76ca59bca4ccd161c2687050878c47289a98407a23372",
+    "zh:d692fc33b67ac89e916c8f9233d39eacab8c438fe10172990ee9d94fba5ca372",
+    "zh:d9075c7da48947c029ba47d5985e1e8e3bf92367bfee8ca1ff0e747765e779a1",
+    "zh:e81c62db317f3b640b2e04eba0ada8aa606bcbae0152c09f6242e86b86ef5889",
+    "zh:f68562e073722c378d2f3529eb80ad463f12c44aa5523d558ae3b69f4de5ca1f",
+  ]
+}
+
+provider "registry.terraform.io/hashicorp/tls" {
+  version = "4.0.6"
+  hashes = [
+    "h1:dYSb3V94K5dDMtrBRLPzBpkMTPn+3cXZ/kIJdtFL+2M=",
+    "zh:10de0d8af02f2e578101688fd334da3849f56ea91b0d9bd5b1f7a243417fdda8",
+    "zh:37fc01f8b2bc9d5b055dc3e78bfd1beb7c42cfb776a4c81106e19c8911366297",
+    "zh:4578ca03d1dd0b7f572d96bd03f744be24c726bfd282173d54b100fd221608bb",
+    "zh:6c475491d1250050765a91a493ef330adc24689e8837a0f07da5a0e1269e11c1",
+    "zh:81bde94d53cdababa5b376bbc6947668be4c45ab655de7aa2e8e4736dfd52509",
+    "zh:abdce260840b7b050c4e401d4f75c7a199fafe58a8b213947a258f75ac18b3e8",
+    "zh:b754cebfc5184873840f16a642a7c9ef78c34dc246a8ae29e056c79939963c7a",
+    "zh:c928b66086078f9917aef0eec15982f2e337914c5c4dbc31dd4741403db7eb18",
+    "zh:cded27bee5f24de6f2ee0cfd1df46a7f88e84aaffc2ecbf3ff7094160f193d50",
+    "zh:d65eb3867e8f69aaf1b8bb53bd637c99c6b649ba3db16ded50fa9a01076d1a27",
+    "zh:ecb0c8b528c7a619fa71852bb3fb5c151d47576c5aab2bf3af4db52588722eeb",
+    "zh:f569b65999264a9416862bca5cd2a6177d94ccb0424f3a4ef424428912b9cb3c",
+  ]
+}
+
+provider "registry.terraform.io/petoju/mysql" {
+  version     = "3.0.71"
+  constraints = "3.0.71"
+  hashes = [
+    "h1:Xwam63rfo59cWPri28xmAbuqrFsxHwAE1P7ogpMUdSU=",
+    "zh:15200cd22d5a03fafb41cc2ffc654ab58cbcea80920e280ce08b46b3a8378813",
+    "zh:16e2cc6d38d5be31c59412ced68b451129f3d048d4debb3afaf5603befdfbf50",
+    "zh:31e9f6cc515378f3bec1fca57892b7e3224442801ac95c18ba83148e793dbc8e",
+    "zh:3c456ab07b34c8b472b050c3ef333b469164a85bb79c0e5a87ac0dc7aa45eb22",
+    "zh:538ffa7821989fabd763227fb85aebbd85df57dba9fffc2e060306761b320110",
+    "zh:69cdda5e80dfb4ca71ef44d719abdee9c9250153ac2269b3a3d17a679f3fb858",
+    "zh:87eb21da93c9ac51f74c5e8cf53690e51fc0561cfbe14d953c342eb583f31d22",
+    "zh:8db301a9ae9fc6374fb5cc42bbf81c0f0ea1e7f46f447de56dd752dcecb3c43f",
+    "zh:a1878a45070ec92659a39e265848fcbdd0f1423dc8eb8cc764c690f73c4430a5",
+    "zh:a9c9029784f7273d9c153d0a4291b493d68049193068bef4f0374dcaf379e67c",
+    "zh:ac91bc2538d87b4cf703d2bdae2ceab8567235a9d29c0de8b74bcde0eb828f75",
+    "zh:b95a21d4857fe84a7e8edc3ff5a828c37a9a99eb1e116045603a0bf00b1dcb89",
+    "zh:bf38af7e3cde5a717fa67e1e7e936550cb6d3197774e575f13ef974ec92061d2",
+    "zh:e3d481f0c7a47744c40dabe731082f1730d7ae55417257f4f49404b1a93701b8",
+  ]
+}
diff --git a/deployment/live/aws/test/.terraform.lock.hcl b/deployment/live/aws/test/.terraform.lock.hcl
index fa046975..a9e266b5 100644
--- a/deployment/live/aws/test/.terraform.lock.hcl
+++ b/deployment/live/aws/test/.terraform.lock.hcl
@@ -41,4 +41,26 @@ provider "registry.terraform.io/hashicorp/tls" {
     "zh:ecb0c8b528c7a619fa71852bb3fb5c151d47576c5aab2bf3af4db52588722eeb",
     "zh:f569b65999264a9416862bca5cd2a6177d94ccb0424f3a4ef424428912b9cb3c",
   ]
-}
\ No newline at end of file
+}
+
+provider "registry.terraform.io/petoju/mysql" {
+  version     = "3.0.71"
+  constraints = "3.0.71"
+  hashes = [
+    "h1:Xwam63rfo59cWPri28xmAbuqrFsxHwAE1P7ogpMUdSU=",
+    "zh:15200cd22d5a03fafb41cc2ffc654ab58cbcea80920e280ce08b46b3a8378813",
+    "zh:16e2cc6d38d5be31c59412ced68b451129f3d048d4debb3afaf5603befdfbf50",
+    "zh:31e9f6cc515378f3bec1fca57892b7e3224442801ac95c18ba83148e793dbc8e",
+    "zh:3c456ab07b34c8b472b050c3ef333b469164a85bb79c0e5a87ac0dc7aa45eb22",
+    "zh:538ffa7821989fabd763227fb85aebbd85df57dba9fffc2e060306761b320110",
+    "zh:69cdda5e80dfb4ca71ef44d719abdee9c9250153ac2269b3a3d17a679f3fb858",
+    "zh:87eb21da93c9ac51f74c5e8cf53690e51fc0561cfbe14d953c342eb583f31d22",
+    "zh:8db301a9ae9fc6374fb5cc42bbf81c0f0ea1e7f46f447de56dd752dcecb3c43f",
+    "zh:a1878a45070ec92659a39e265848fcbdd0f1423dc8eb8cc764c690f73c4430a5",
+    "zh:a9c9029784f7273d9c153d0a4291b493d68049193068bef4f0374dcaf379e67c",
+    "zh:ac91bc2538d87b4cf703d2bdae2ceab8567235a9d29c0de8b74bcde0eb828f75",
+    "zh:b95a21d4857fe84a7e8edc3ff5a828c37a9a99eb1e116045603a0bf00b1dcb89",
+    "zh:bf38af7e3cde5a717fa67e1e7e936550cb6d3197774e575f13ef974ec92061d2",
+    "zh:e3d481f0c7a47744c40dabe731082f1730d7ae55417257f4f49404b1a93701b8",
+  ]
+}
diff --git a/deployment/live/aws/test/README.md b/deployment/live/aws/test/README.md
index 0ea6ab90..8f2e9fba 100644
--- a/deployment/live/aws/test/README.md
+++ b/deployment/live/aws/test/README.md
@@ -66,14 +66,18 @@ export AWS_PROFILE=AdministratorAccess-<REDACTED>
 
 Terraforming the account can be done by:
   1. `cd` to [/deployment/live/aws/test/](/deployment/live/aws/test/) to deploy/change.
-  2. Run `terragrunt apply`.
-
+  2. Run `terragrunt apply`. If this fails to create the antispam database,
+  connect the RDS instance to your VM using the instructions below, and run
+  `terragrunt apply` again.
+  
 Store the Aurora RDS database and S3 bucket information into the environment variables:
 
 ```sh
 export TESSERACT_DB_HOST=$(terragrunt output -raw rds_aurora_cluster_endpoint)
 export TESSERACT_DB_PASSWORD=$(aws secretsmanager get-secret-value --secret-id $(terragrunt output -json rds_aurora_cluster_master_user_secret | jq --raw-output .[0].secret_arn) --query SecretString --output text | jq --raw-output .password)
 export TESSERACT_BUCKET_NAME=$(terragrunt output -raw s3_bucket_name)
+export SCTFE_SIGNER_ECDSA_P256_PUBLIC_KEY_ID=$(terragrunt output -raw ecdsa_p256_public_key_id)
+export SCTFE_SIGNER_ECDSA_P256_PRIVATE_KEY_ID=$(terragrunt output -raw ecdsa_p256_private_key_id)
 ```
 
 Connect the VM and Aurora database following [these instructions](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/tutorial-ec2-rds-option1.html#option1-task3-connect-ec2-instance-to-rds-database), it takes a few clicks in the UI.
@@ -95,7 +99,9 @@ go run ./cmd/aws \
   --db_port=3306 \
   --db_user=tesseract \
   --db_password=${TESSERACT_DB_PASSWORD} \
-  --dedup_path=test-static-ct
+  --antispam_db_name=antispam_db \
+  --signer_public_key_secret_name=${SCTFE_SIGNER_ECDSA_P256_PUBLIC_KEY_ID} \
+  --signer_private_key_secret_name=${SCTFE_SIGNER_ECDSA_P256_PRIVATE_KEY_ID}
 ```
 
 In a different terminal you can either mint and submit certificates manually, or
@@ -187,7 +193,9 @@ go run ./cmd/aws \
   --db_port=3306 \
   --db_user=tesseract \
   --db_password=${TESSERACT_DB_PASSWORD} \
-  --dedup_path=test-static-ct
+  --antispam_db_name=antispam_db \
+  --signer_public_key_secret_name=${SCTFE_SIGNER_ECDSA_P256_PUBLIC_KEY_ID} \
+  --signer_private_key_secret_name=${SCTFE_SIGNER_ECDSA_P256_PRIVATE_KEY_ID}
   -v=3
 ```
 
diff --git a/deployment/live/gcp/static-ct/logs/ci/README.md b/deployment/live/gcp/static-ct/logs/ci/README.md
index acf5a4e5..86306162 100644
--- a/deployment/live/gcp/static-ct/logs/ci/README.md
+++ b/deployment/live/gcp/static-ct/logs/ci/README.md
@@ -8,7 +8,7 @@ define a CI environment to run the SCTFE on Cloud Run, backed by Trillian Tesser
 At a high level, this environment consists of:
 - One Spanner instance with two databases:
   - one for Tessera
-  - one for deduplication
+  - one for antispam 
 - A GCS Bucket
 - Secret Manager
 - Cloud Run
diff --git a/deployment/live/gcp/test/README.md b/deployment/live/gcp/test/README.md
index d330cbb0..2dc8e255 100644
--- a/deployment/live/gcp/test/README.md
+++ b/deployment/live/gcp/test/README.md
@@ -14,7 +14,7 @@ define a test environment to run the SCTFE, backed by Trillian Tessera.
 At a high level, this environment consists of:
 - One Spanner instance with two databases:
   - one for Tessera
-  - one for deduplication
+  - one for antispam
 - A GCS Bucket
 - Secret Manager
 
@@ -56,7 +56,7 @@ On the VM, run the following command to bring up the SCTFE:
 go run ./cmd/gcp/ \
   --bucket=${GOOGLE_PROJECT}-${TESSERA_BASE_NAME}-bucket \
   --spanner_db_path=projects/${GOOGLE_PROJECT}/instances/${TESSERA_BASE_NAME}/databases/${TESSERA_BASE_NAME}-db \
-  --spanner_dedup_db_path=projects/${GOOGLE_PROJECT}/instances/${TESSERA_BASE_NAME}/databases/${TESSERA_BASE_NAME}-dedup-db \
+  --spanner_antispam_db_path=projects/${GOOGLE_PROJECT}/instances/${TESSERA_BASE_NAME}/databases/${TESSERA_BASE_NAME}-antispam-db \
   --roots_pem_file=./internal/testdata/fake-ca.cert \
   --origin=${TESSERA_BASE_NAME} \
   --signer_public_key_secret_name=${SCTFE_SIGNER_ECDSA_P256_PUBLIC_KEY_ID} \
@@ -147,7 +147,7 @@ go run ./cmd/gcp/ \
   --spanner_db_path=projects/${GOOGLE_PROJECT}/instances/${TESSERA_BASE_NAME}/databases/${TESSERA_BASE_NAME}-db \
   --roots_pem_file=/tmp/hammercfg/roots.pem \
   --origin=${TESSERA_BASE_NAME} \
-  --spanner_dedup_db_path=projects/${GOOGLE_PROJECT}/instances/${TESSERA_BASE_NAME}/databases/${TESSERA_BASE_NAME}-dedup-db \
+  --spanner_antispam_db_path=projects/${GOOGLE_PROJECT}/instances/${TESSERA_BASE_NAME}/databases/${TESSERA_BASE_NAME}-antispam-db \
   --signer_public_key_secret_name=${SCTFE_SIGNER_ECDSA_P256_PUBLIC_KEY_ID} \
   --signer_private_key_secret_name=${SCTFE_SIGNER_ECDSA_P256_PRIVATE_KEY_ID} \
   -v=3
diff --git a/deployment/modules/aws/storage/main.tf b/deployment/modules/aws/storage/main.tf
index 3e5af201..d585a5f2 100644
--- a/deployment/modules/aws/storage/main.tf
+++ b/deployment/modules/aws/storage/main.tf
@@ -4,6 +4,10 @@ terraform {
       source  = "hashicorp/aws"
       version = "5.92.0"
     }
+    mysql = {
+      source  = "petoju/mysql"
+      version = "3.0.71"
+    }
   }
 }
 
@@ -50,3 +54,20 @@ data "aws_secretsmanager_secret_version" "db_credentials" {
     aws_rds_cluster_instance.cluster_instances
   ]
 }
+
+# Configure the MySQL provider based on the outcome of
+# creating the aws_db_instance.
+# This requires that the machine running terraform has access
+# to the DB instance created above. This is _NOT_ the case when
+# GitHub actions are applying the terraform.
+provider "mysql" {
+  endpoint = aws_rds_cluster_instance.cluster_instances[0].endpoint
+  username = aws_rds_cluster.log_rds_cluster.master_username
+  password = jsondecode(data.aws_secretsmanager_secret_version.db_credentials.secret_string)["password"]
+}
+
+# Create a second database for antispam.
+resource "mysql_database" "antispam_db" {
+  name  = "antispam_db"
+  count = var.create_antispam_db ? 1 : 0
+}
diff --git a/deployment/modules/aws/storage/outputs.tf b/deployment/modules/aws/storage/outputs.tf
index 1b05d0de..b9c13ddc 100644
--- a/deployment/modules/aws/storage/outputs.tf
+++ b/deployment/modules/aws/storage/outputs.tf
@@ -33,3 +33,7 @@ output "rds_aurora_cluster_master_user_secret_unsafe" {
   value       = jsondecode(data.aws_secretsmanager_secret_version.db_credentials.secret_string)["password"]
   sensitive   = true # Mark as sensitive, but it can still be exposed
 }
+
+output "antispam_database_name" {
+  value = mysql_database.antispam_db[0].name
+}
diff --git a/deployment/modules/aws/storage/variables.tf b/deployment/modules/aws/storage/variables.tf
index 530c1312..cb59fccf 100644
--- a/deployment/modules/aws/storage/variables.tf
+++ b/deployment/modules/aws/storage/variables.tf
@@ -13,6 +13,12 @@ variable "region" {
   type        = string
 }
 
+variable "create_antispam_db" {
+  description = "Set to true to create another database to be used by the antispam implementation."
+  type        = bool
+  default     = false
+}
+
 variable "ephemeral" {
   description = "Set to true if this is a throwaway/temporary log instance. Will set attributes on created resources to allow them to be disabled/deleted more easily."
   type        = bool
diff --git a/deployment/modules/aws/tesseract/conformance/main.tf b/deployment/modules/aws/tesseract/conformance/main.tf
index 2a95de6b..57f5cff3 100644
--- a/deployment/modules/aws/tesseract/conformance/main.tf
+++ b/deployment/modules/aws/tesseract/conformance/main.tf
@@ -16,10 +16,11 @@ locals {
 module "storage" {
   source = "../../storage"
 
-  prefix_name = var.prefix_name
-  base_name   = var.base_name
-  region      = var.region
-  ephemeral   = var.ephemeral
+  prefix_name        = var.prefix_name
+  base_name          = var.base_name
+  region             = var.region
+  ephemeral          = var.ephemeral
+  create_antispam_db = true
 }
 
 module "secretsmanager" {
@@ -168,9 +169,10 @@ resource "aws_ecs_task_definition" "conformance" {
       "--db_name=tesseract",
       "--db_host=${module.storage.rds_aurora_cluster_endpoint}",
       "--db_port=3306",
-      "--dedup_path=ci-static-ct",
       "--signer_public_key_secret_name=${module.secretsmanager.ecdsa_p256_public_key_id}",
       "--signer_private_key_secret_name=${module.secretsmanager.ecdsa_p256_private_key_id}",
+      "--antispam_db_name=${module.storage.antispam_database_name}",
+      "--inmemory_antispam_cache_size=25000000", # About 1GB of memory.
       "-v=2"
     ],
     "logConfiguration" : {
diff --git a/deployment/modules/aws/tesseract/test/main.tf b/deployment/modules/aws/tesseract/test/main.tf
index a479898a..4c1748e9 100644
--- a/deployment/modules/aws/tesseract/test/main.tf
+++ b/deployment/modules/aws/tesseract/test/main.tf
@@ -5,10 +5,11 @@ terraform {
 module "storage" {
   source = "../../storage"
 
-  prefix_name = var.prefix_name
-  base_name   = var.base_name
-  region      = var.region
-  ephemeral   = var.ephemeral
+  prefix_name        = var.prefix_name
+  base_name          = var.base_name
+  region             = var.region
+  ephemeral          = var.ephemeral
+  create_antispam_db = true
 }
 
 module "secretsmanager" {
diff --git a/deployment/modules/gcp/cloudrun/main.tf b/deployment/modules/gcp/cloudrun/main.tf
index 1c0d2bed..4b16a1a5 100644
--- a/deployment/modules/gcp/cloudrun/main.tf
+++ b/deployment/modules/gcp/cloudrun/main.tf
@@ -12,7 +12,7 @@ terraform {
 locals {
   cloudrun_service_account_id = var.env == "" ? "cloudrun-sa" : "cloudrun-${var.env}-sa"
   spanner_log_db_path         = "projects/${var.project_id}/instances/${var.log_spanner_instance}/databases/${var.log_spanner_db}"
-  spanner_dedup_db_path       = "projects/${var.project_id}/instances/${var.log_spanner_instance}/databases/${var.dedup_spanner_db}"
+  spanner_antispam_db_path    = "projects/${var.project_id}/instances/${var.log_spanner_instance}/databases/${var.antispam_spanner_db}"
 }
 
 resource "google_project_service" "cloudrun_api" {
@@ -44,11 +44,12 @@ resource "google_cloud_run_v2_service" "default" {
         "--http_endpoint=:6962",
         "--bucket=${var.bucket}",
         "--spanner_db_path=${local.spanner_log_db_path}",
-        "--spanner_dedup_db_path=${local.spanner_dedup_db_path}",
+        "--spanner_antispam_db_path=${local.spanner_antispam_db_path}",
         "--roots_pem_file=/bin/test_root_ca_cert.pem",
         "--origin=${var.base_name}${var.origin_suffix}",
         "--signer_public_key_secret_name=${var.signer_public_key_secret_name}",
         "--signer_private_key_secret_name=${var.signer_private_key_secret_name}",
+      	"--inmemory_antispam_cache_size=25000000", # About 1GB of memory.
       ]
       ports {
         container_port = 6962
diff --git a/deployment/modules/gcp/cloudrun/variables.tf b/deployment/modules/gcp/cloudrun/variables.tf
index f77b7812..3d8ae310 100644
--- a/deployment/modules/gcp/cloudrun/variables.tf
+++ b/deployment/modules/gcp/cloudrun/variables.tf
@@ -43,8 +43,8 @@ variable "log_spanner_db" {
   type        = string
 }
 
-variable "dedup_spanner_db" {
-  description = "Dedup Spanner database"
+variable "antispam_spanner_db" {
+  description = "Antispam Spanner database"
   type        = string
 }
 
diff --git a/deployment/modules/gcp/storage/main.tf b/deployment/modules/gcp/storage/main.tf
index 6cf259dd..5a9fb644 100644
--- a/deployment/modules/gcp/storage/main.tf
+++ b/deployment/modules/gcp/storage/main.tf
@@ -64,11 +64,12 @@ resource "google_spanner_database" "log_db" {
   deletion_protection = !var.ephemeral
 }
 
-resource "google_spanner_database" "dedup_db" {
+resource "google_spanner_database" "antispam_db" {
   instance = google_spanner_instance.log_spanner.name
-  name     = "${var.base_name}-dedup-db"
+  name     = "${var.base_name}-antispam-db"
   ddl = [
-    "CREATE TABLE IDSeq (id INT64 NOT NULL, h BYTES(MAX) NOT NULL, idx INT64 NOT NULL, timestamp INT64 NOT NULL,) PRIMARY KEY (id, h)",
+    "CREATE TABLE IF NOT EXISTS FollowCoord (id INT64 NOT NULL, nextIdx INT64 NOT NULL) PRIMARY KEY (id)",
+    "CREATE TABLE IF NOT EXISTS IDSeq (h BYTES(32) NOT NULL, idx INT64 NOT NULL) PRIMARY KEY (h)",
   ]
 
   deletion_protection = !var.ephemeral
diff --git a/deployment/modules/gcp/storage/outputs.tf b/deployment/modules/gcp/storage/outputs.tf
index 578b9ffa..bbbd74cc 100644
--- a/deployment/modules/gcp/storage/outputs.tf
+++ b/deployment/modules/gcp/storage/outputs.tf
@@ -13,7 +13,7 @@ output "log_spanner_db" {
   value       = google_spanner_database.log_db
 }
 
-output "dedup_spanner_db" {
-  description = "Dedup Spanner database"
-  value       = google_spanner_database.dedup_db
+output "antispam_spanner_db" {
+  description = "Antispam Spanner database"
+  value       = google_spanner_database.antispam_db
 }
diff --git a/deployment/modules/gcp/tesseract/cloudrun/main.tf b/deployment/modules/gcp/tesseract/cloudrun/main.tf
index 42344e3a..786a537f 100644
--- a/deployment/modules/gcp/tesseract/cloudrun/main.tf
+++ b/deployment/modules/gcp/tesseract/cloudrun/main.tf
@@ -30,7 +30,7 @@ module "cloudrun" {
   bucket                         = module.storage.log_bucket.id
   log_spanner_instance           = module.storage.log_spanner_instance.name
   log_spanner_db                 = module.storage.log_spanner_db.name
-  dedup_spanner_db               = module.storage.dedup_spanner_db.name
+  antispam_spanner_db            = module.storage.antispam_spanner_db.name
   signer_public_key_secret_name  = module.secretmanager.ecdsa_p256_public_key_id
   signer_private_key_secret_name = module.secretmanager.ecdsa_p256_private_key_id
 
diff --git a/go.mod b/go.mod
index 08a5de5f..8af928a2 100644
--- a/go.mod
+++ b/go.mod
@@ -67,6 +67,9 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/sts v1.33.19 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/cncf/xds/go v0.0.0-20250121191232-2f005788dc42 // indirect
+	github.com/dgraph-io/badger/v4 v4.7.0 // indirect
+	github.com/dgraph-io/ristretto/v2 v2.2.0 // indirect
+	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/envoyproxy/go-control-plane/envoy v1.32.4 // indirect
 	github.com/envoyproxy/protoc-gen-validate v1.2.1 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
@@ -76,11 +79,13 @@ require (
 	github.com/go-logr/logr v1.4.2 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/golang/groupcache v0.0.0-20241129210726-2c02b8208cf8 // indirect
+	github.com/google/flatbuffers v25.2.10+incompatible // indirect
 	github.com/google/s2a-go v0.1.9 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.6 // indirect
 	github.com/googleapis/gax-go/v2 v2.14.1 // indirect
 	github.com/hashicorp/golang-lru/v2 v2.0.7 // indirect
+	github.com/klauspost/compress v1.18.0 // indirect
 	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
 	github.com/mattn/go-runewidth v0.0.16 // indirect
 	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
diff --git a/go.sum b/go.sum
index 790527ed..13d32870 100644
--- a/go.sum
+++ b/go.sum
@@ -724,8 +724,14 @@ github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/dgraph-io/badger/v4 v4.7.0 h1:Q+J8HApYAY7UMpL8d9owqiB+odzEc0zn/aqOD9jhc6Y=
+github.com/dgraph-io/badger/v4 v4.7.0/go.mod h1:He7TzG3YBy3j4f5baj5B7Zl2XyfNe5bl4Udl0aPemVA=
+github.com/dgraph-io/ristretto/v2 v2.2.0 h1:bkY3XzJcXoMuELV8F+vS8kzNgicwQFAaGINAEJdWGOM=
+github.com/dgraph-io/ristretto/v2 v2.2.0/go.mod h1:RZrm63UmcBAaYWC1DotLYBmTvgkrs0+XhBd7Npn7/zI=
 github.com/docopt/docopt-go v0.0.0-20180111231733-ee0de3bc6815/go.mod h1:WwZ+bS3ebgob9U8Nd0kOddGdZWjyMGR8Wziv+TBNwSE=
 github.com/dustin/go-humanize v1.0.0/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
+github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
+github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1mIlRU8Am5FuJP05cCM98=
@@ -831,6 +837,8 @@ github.com/golang/snappy v0.0.4/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEW
 github.com/google/btree v0.0.0-20180813153112-4030bb1f1f0c/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
 github.com/google/btree v1.0.0/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
 github.com/google/flatbuffers v2.0.8+incompatible/go.mod h1:1AeVuKshWv4vARoZatz6mlQ0JxURH0Kv5+zNeJKJCa8=
+github.com/google/flatbuffers v25.2.10+incompatible h1:F3vclr7C3HpB1k9mxCGRMXq6FdUalZ6H/pNX4FP1v0Q=
+github.com/google/flatbuffers v25.2.10+incompatible/go.mod h1:1AeVuKshWv4vARoZatz6mlQ0JxURH0Kv5+zNeJKJCa8=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
@@ -920,6 +928,8 @@ github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51/go.mod h1:C
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/klauspost/asmfmt v1.3.2/go.mod h1:AG8TuvYojzulgDAMCnYn50l/5QV3Bs/tp6j0HLHbNSE=
 github.com/klauspost/compress v1.15.9/go.mod h1:PhcZ0MbTNciWF3rruxRgKxI5NkcHHrHUDtV4Yw2GlzU=
+github.com/klauspost/compress v1.18.0 h1:c/Cqfb0r+Yi+JtIEq73FWXVkRonBlf0CRNYc8Zttxdo=
+github.com/klauspost/compress v1.18.0/go.mod h1:2Pp+KzxcywXVXMr50+X0Q/Lsb43OQHYWRCY2AiWywWQ=
 github.com/klauspost/cpuid/v2 v2.0.9/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
 github.com/kr/fs v0.1.0/go.mod h1:FFnZGqtBN9Gxj7eW1uZ42v5BccTP0vu6NEaFoC2HwRg=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
diff --git a/internal/ct/ctlog.go b/internal/ct/ctlog.go
index c516a22b..51f85f90 100644
--- a/internal/ct/ctlog.go
+++ b/internal/ct/ctlog.go
@@ -9,9 +9,7 @@ import (
 	"fmt"
 
 	"github.com/transparency-dev/static-ct/internal/types/rfc6962"
-	"github.com/transparency-dev/static-ct/modules/dedup"
 	"github.com/transparency-dev/static-ct/storage"
-	tessera "github.com/transparency-dev/trillian-tessera"
 	"github.com/transparency-dev/trillian-tessera/ctonly"
 	"k8s.io/klog/v2"
 )
@@ -36,13 +34,9 @@ type signSCT func(leaf *rfc6962.MerkleTreeLeaf) (*rfc6962.SignedCertificateTimes
 // Storage provides functions to store certificates in a static-ct-api log.
 type Storage interface {
 	// Add assigns an index to the provided Entry, stages the entry for integration, and returns a future for the assigned index.
-	Add(context.Context, *ctonly.Entry) tessera.IndexFuture
+	Add(context.Context, *ctonly.Entry) (idx uint64, timestamp uint64, err error)
 	// AddIssuerChain stores every the chain certificate in a content-addressable store under their sha256 hash.
 	AddIssuerChain(context.Context, []*x509.Certificate) error
-	// AddCertDedupInfo stores the SCTDedupInfo of certificate in a log under its hash.
-	AddCertDedupInfo(context.Context, *x509.Certificate, dedup.SCTDedupInfo) error
-	// GetCertDedupInfo gets the SCTDedupInfo of certificate in a log from its hash.
-	GetCertDedupInfo(context.Context, *x509.Certificate) (dedup.SCTDedupInfo, bool, error)
 }
 
 // ChainValidator provides functions to validate incoming chains.
diff --git a/internal/ct/handlers.go b/internal/ct/handlers.go
index 07534789..95766f8a 100644
--- a/internal/ct/handlers.go
+++ b/internal/ct/handlers.go
@@ -30,7 +30,6 @@ import (
 	"github.com/transparency-dev/static-ct/internal/types/rfc6962"
 	"github.com/transparency-dev/static-ct/internal/types/tls"
 	"github.com/transparency-dev/static-ct/internal/x509util"
-	"github.com/transparency-dev/static-ct/modules/dedup"
 	tessera "github.com/transparency-dev/trillian-tessera"
 	"go.opentelemetry.io/otel/metric"
 	"k8s.io/klog/v2"
@@ -69,7 +68,9 @@ var (
 
 // setupMetrics initializes all the exported metrics.
 func setupMetrics() {
-	// TODO(phboneff): add metrics for deduplication and chain storage.
+	// TODO(phboneff): add metrics for chain storage.
+	// TODO(phboneff): add metrics for deduplication.
+	// TODO(phboneff): break down metrics by whether or not the response has been deduped.
 	knownLogs = mustCreate(meter.Int64Gauge("tesseract.known_logs",
 		metric.WithDescription("Set to 1 for known logs")))
 
@@ -120,11 +121,11 @@ func (a appHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	originAttr := originKey.String(a.log.origin)
 	operationAttr := operationKey.String(a.name)
 	reqCounter.Add(r.Context(), 1, metric.WithAttributes(originAttr, operationAttr))
-	startTime := a.opts.TimeSource.Now()
+	startTime := time.Now()
 	logCtx := a.opts.RequestLog.start(r.Context())
 	a.opts.RequestLog.origin(logCtx, a.log.origin)
 	defer func() {
-		latency := a.opts.TimeSource.Now().Sub(startTime).Seconds()
+		latency := time.Since(startTime).Seconds()
 		reqDuration.Record(r.Context(), latency, metric.WithAttributes(originAttr, operationAttr, codeKey.Int(statusCode)))
 	}()
 
@@ -148,7 +149,8 @@ func (a appHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// impose a deadline on this onward request.
-	ctx, cancel := context.WithDeadline(logCtx, deadlineTime(a.opts))
+	// TODO(phbnf): fine tune together with deduplication
+	ctx, cancel := context.WithTimeout(logCtx, a.opts.Deadline)
 	defer cancel()
 
 	var err error
@@ -180,6 +182,7 @@ type HandlerOptions struct {
 	// or returned to the user containing the full error message.
 	MaskInternalErrors bool
 	// TimeSource indicated the system time and can be injfected for testing.
+	// TODO(phbnf): hide inside the log
 	TimeSource TimeSource
 }
 
@@ -271,47 +274,24 @@ func addChainInternal(ctx context.Context, opts *HandlerOptions, log *log, w htt
 		return http.StatusBadRequest, fmt.Errorf("failed to build MerkleTreeLeaf: %s", err)
 	}
 
-	klog.V(2).Infof("%s: %s => storage.GetCertIndex", log.origin, method)
-	sctDedupInfo, isDup, err := log.storage.GetCertDedupInfo(ctx, chain[0])
-	idx := sctDedupInfo.Idx
-	if err != nil {
-		return http.StatusInternalServerError, fmt.Errorf("couldn't deduplicate the request: %s", err)
+	if err := log.storage.AddIssuerChain(ctx, chain[1:]); err != nil {
+		return http.StatusInternalServerError, fmt.Errorf("failed to store issuer chain: %s", err)
 	}
 
-	if isDup {
-		klog.V(3).Infof("%s: %s - found duplicate entry at index %d", log.origin, method, idx)
-		entry.Timestamp = sctDedupInfo.Timestamp
-	} else {
-		if err := log.storage.AddIssuerChain(ctx, chain[1:]); err != nil {
-			return http.StatusInternalServerError, fmt.Errorf("failed to store issuer chain: %s", err)
-		}
-
-		klog.V(2).Infof("%s: %s => storage.Add", log.origin, method)
-		index, err := log.storage.Add(ctx, entry)()
-		if err != nil {
-			if errors.Is(err, tessera.ErrPushback) {
-				w.Header().Add("Retry-After", "1")
-				return http.StatusServiceUnavailable, fmt.Errorf("received pushback from Tessera sequencer: %v", err)
-			}
-			return http.StatusInternalServerError, fmt.Errorf("couldn't store the leaf: %v", err)
-		}
-		// TODO(phbnf): figure out whether to use Tessera's index.IsDup() or a separate "external" antispam impl.
-		idx = index.Index
-
-		// We store the index for this certificate in the deduplication storage immediately.
-		// It might be stored again later, if a local deduplication storage is synced, potentially
-		// with a smaller value.
-		klog.V(2).Infof("%s: %s => storage.AddCertIndex", log.origin, method)
-		err = log.storage.AddCertDedupInfo(ctx, chain[0], dedup.SCTDedupInfo{Idx: idx, Timestamp: entry.Timestamp})
-		// TODO: block log writes if deduplication breaks
-		if err != nil {
-			klog.Warningf("AddCertIndex(): failed to store certificate index: %v", err)
+	klog.V(2).Infof("%s: %s => storage.Add", log.origin, method)
+	index, dedupedTimeMillis, err := log.storage.Add(ctx, entry)
+	if err != nil {
+		if errors.Is(err, tessera.ErrPushback) {
+			w.Header().Add("Retry-After", "1")
+			return http.StatusServiceUnavailable, fmt.Errorf("received pushback from Tessera sequencer: %v", err)
 		}
+		return http.StatusInternalServerError, fmt.Errorf("couldn't store the leaf: %v", err)
 	}
+	entry.Timestamp = dedupedTimeMillis
 
 	// Always use the returned leaf as the basis for an SCT.
 	var loggedLeaf rfc6962.MerkleTreeLeaf
-	leafValue := entry.MerkleTreeLeaf(idx)
+	leafValue := entry.MerkleTreeLeaf(index)
 	if rest, err := tls.Unmarshal(leafValue, &loggedLeaf); err != nil {
 		return http.StatusInternalServerError, fmt.Errorf("failed to reconstruct MerkleTreeLeaf: %s", err)
 	} else if len(rest) > 0 {
@@ -338,7 +318,7 @@ func addChainInternal(ctx context.Context, opts *HandlerOptions, log *log, w htt
 	klog.V(3).Infof("%s: %s <= SCT", log.origin, method)
 	if sct.Timestamp == timeMillis {
 		lastSCTTimestamp.Record(ctx, otel.Clamp64(sct.Timestamp), metric.WithAttributes(originKey.String(log.origin)))
-		lastSCTIndex.Record(ctx, otel.Clamp64(idx), metric.WithAttributes(originKey.String(log.origin)))
+		lastSCTIndex.Record(ctx, otel.Clamp64(index), metric.WithAttributes(originKey.String(log.origin)))
 	}
 
 	return http.StatusOK, nil
@@ -381,11 +361,6 @@ func getRoots(ctx context.Context, opts *HandlerOptions, log *log, w http.Respon
 	return http.StatusOK, nil
 }
 
-// deadlineTime calculates the future time a request should expire based on our config.
-func deadlineTime(opts *HandlerOptions) time.Time {
-	return opts.TimeSource.Now().Add(opts.Deadline)
-}
-
 // marshalAndWriteAddChainResponse is used by add-chain and add-pre-chain to create and write
 // the JSON response to the client
 func marshalAndWriteAddChainResponse(sct *rfc6962.SignedCertificateTimestamp, w http.ResponseWriter) error {
diff --git a/internal/ct/handlers_test.go b/internal/ct/handlers_test.go
index 4b979ae0..fb823e0e 100644
--- a/internal/ct/handlers_test.go
+++ b/internal/ct/handlers_test.go
@@ -41,11 +41,11 @@ import (
 	"github.com/transparency-dev/static-ct/internal/types/staticct"
 	"github.com/transparency-dev/static-ct/internal/x509util"
 	"github.com/transparency-dev/static-ct/storage"
-	"github.com/transparency-dev/static-ct/storage/bbolt"
 	tessera "github.com/transparency-dev/trillian-tessera"
 	"github.com/transparency-dev/trillian-tessera/api/layout"
 	"github.com/transparency-dev/trillian-tessera/ctonly"
 	posixTessera "github.com/transparency-dev/trillian-tessera/storage/posix"
+	badger_as "github.com/transparency-dev/trillian-tessera/storage/posix/antispam"
 	"golang.org/x/mod/sumdb/note"
 	"k8s.io/klog/v2"
 )
@@ -55,8 +55,10 @@ var (
 	testRootPath = "../testdata/test_root_ca_cert.pem"
 
 	// Arbitrary time for use in tests
-	fakeTime       = time.Date(2016, 7, 22, 11, 01, 13, 0, time.UTC)
-	fakeTimeMillis = uint64(fakeTime.UnixNano() / nanosPerMilli)
+	fakeTimeStart = time.Date(2016, 7, 22, 11, 01, 13, 0, time.UTC)
+	// TODO(phbnf): this doesn't need to be gloabal, but it easier until
+	// TimeSource belongs to hOpts.
+	timeSource = newFakeTimeSource(fakeTimeStart)
 
 	// Arbitrary origin for tests
 	origin = "example.com"
@@ -64,10 +66,10 @@ var (
 
 	// Default handler options for tests
 	hOpts = HandlerOptions{
-		Deadline:           time.Millisecond * 500,
+		Deadline:           time.Millisecond * 2000,
 		RequestLog:         &DefaultRequestLog{},
 		MaskInternalErrors: false,
-		TimeSource:         newFixedTimeSource(fakeTime),
+		TimeSource:         timeSource,
 	}
 
 	// POSIX subdirectories
@@ -79,16 +81,26 @@ type fixedTimeSource struct {
 	fakeTime time.Time
 }
 
-// newFixedTimeSource creates a fixedTimeSource instance
-func newFixedTimeSource(t time.Time) *fixedTimeSource {
+// newFakeTimeSource creates a fixedTimeSource instance
+func newFakeTimeSource(t time.Time) *fixedTimeSource {
 	return &fixedTimeSource{fakeTime: t}
 }
 
+// Reset reinitializes the fake time source
+func (f *fixedTimeSource) Reset() {
+	f.fakeTime = fakeTimeStart
+}
+
 // Now returns the time value this instance contains
 func (f *fixedTimeSource) Now() time.Time {
 	return f.fakeTime
 }
 
+// Add1m increments time by 1 minute
+func (f *fixedTimeSource) Add1m() {
+	f.fakeTime = f.fakeTime.Add(time.Minute)
+}
+
 // setupTestLog creates a test TesseraCT log using a POSIX backend.
 //
 // It returns the log and the path to the storage directory.
@@ -112,7 +124,7 @@ func setupTestLog(t *testing.T) (*log, string) {
 		rejectUnexpired: false,
 	}
 
-	log, err := NewLog(t.Context(), origin, sctSigner.signer, cv, newPOSIXStorageFunc(t, storageDir), newFixedTimeSource(fakeTime))
+	log, err := NewLog(t.Context(), origin, sctSigner.signer, cv, newPOSIXStorageFunc(t, storageDir), timeSource)
 	if err != nil {
 		t.Fatalf("newLog(): %v", err)
 	}
@@ -135,8 +147,8 @@ func setupTestServer(t *testing.T, log *log, path string) *httptest.Server {
 
 // newPOSIXStorageFunc returns a function to create a new storage.CTStorage instance with:
 //   - a POSIX Tessera storage driver
+//   - a Badger Tessera antispam database
 //   - a POSIX issuer storage system
-//   - a BBolt deduplication database
 //
 // It also prepares directories to host the log and the deduplication database.
 func newPOSIXStorageFunc(t *testing.T, root string) storage.CreateStorage {
@@ -148,13 +160,22 @@ func newPOSIXStorageFunc(t *testing.T, root string) storage.CreateStorage {
 			klog.Fatalf("Failed to initialize POSIX Tessera storage driver: %v", err)
 		}
 
+		asOpts := badger_as.AntispamOpts{
+			MaxBatchSize:      5000,
+			PushbackThreshold: 1024,
+		}
+		antispam, err := badger_as.NewAntispam(ctx, path.Join(root, "dedup.db"), asOpts)
+		if err != nil {
+			klog.Exitf("Failed to create new GCP antispam storage: %v", err)
+		}
+
 		opts := tessera.NewAppendOptions().
 			WithCheckpointSigner(signer).
-			WithCTLayout()
-			// TODO(phboneff): add other options like MaxBatchSize of 1 when implementing
-			// additional tests
+			WithCTLayout().
+			WithAntispam(256, antispam).
+			WithCheckpointInterval(time.Second)
 
-		appender, _, _, err := tessera.NewAppender(ctx, driver, opts)
+		appender, _, reader, err := tessera.NewAppender(ctx, driver, opts)
 		if err != nil {
 			klog.Fatalf("Failed to initialize POSIX Tessera appender: %v", err)
 		}
@@ -164,12 +185,7 @@ func newPOSIXStorageFunc(t *testing.T, root string) storage.CreateStorage {
 			klog.Fatalf("failed to initialize InMemory issuer storage: %v", err)
 		}
 
-		beDedupStorage, err := bbolt.NewStorage(path.Join(root, "dedup.db"))
-		if err != nil {
-			klog.Fatalf("Failed to initialize BBolt deduplication database: %v", err)
-		}
-
-		s, err := storage.NewCTStorage(appender, issuerStorage, beDedupStorage)
+		s, err := storage.NewCTStorage(t.Context(), appender, issuerStorage, reader)
 		if err != nil {
 			klog.Fatalf("Failed to initialize CTStorage: %v", err)
 		}
@@ -315,7 +331,7 @@ func TestNewPathHandlers(t *testing.T) {
 	})
 }
 
-func parseChain(t *testing.T, isPrecert bool, pemChain []string, root *x509.Certificate) (*ctonly.Entry, []*x509.Certificate) {
+func parseChain(t *testing.T, isPrecert bool, pemChain []string, root *x509.Certificate, timestamp time.Time) (*ctonly.Entry, []*x509.Certificate) {
 	t.Helper()
 	pool := loadCertsIntoPoolOrDie(t, pemChain)
 	leafChain := pool.RawCertificates()
@@ -326,7 +342,7 @@ func parseChain(t *testing.T, isPrecert bool, pemChain []string, root *x509.Cert
 		fullChain[len(leafChain)] = root
 		leafChain = fullChain
 	}
-	entry, err := x509util.EntryFromChain(leafChain, isPrecert, fakeTimeMillis)
+	entry, err := x509util.EntryFromChain(leafChain, isPrecert, uint64(timestamp.UnixMilli()))
 	if err != nil {
 		t.Fatalf("Failed to create entry")
 	}
@@ -444,12 +460,13 @@ func TestAddChainWhitespace(t *testing.T) {
 
 func TestAddChain(t *testing.T) {
 	var tests = []struct {
-		descr       string
-		chain       []string
-		want        int
-		wantIdx     uint64
-		wantLogSize uint64
-		err         error
+		descr         string
+		chain         []string
+		want          int
+		wantIdx       uint64
+		wantLogSize   uint64
+		wantTimestamp time.Time
+		err           error
 	}{
 		{
 			descr: "leaf-only",
@@ -462,45 +479,53 @@ func TestAddChain(t *testing.T) {
 			want:  http.StatusBadRequest,
 		},
 		{
-			descr:       "success",
-			chain:       []string{testdata.CertFromIntermediate, testdata.IntermediateFromRoot, testdata.CACertPEM},
-			wantIdx:     0,
-			wantLogSize: 1,
-			want:        http.StatusOK,
+			descr:         "success",
+			chain:         []string{testdata.CertFromIntermediate, testdata.IntermediateFromRoot, testdata.CACertPEM},
+			wantIdx:       0,
+			wantLogSize:   1,
+			wantTimestamp: fakeTimeStart.Add(3 * time.Minute),
+			want:          http.StatusOK,
 		},
 		{
-			descr:       "success-duplicate",
-			chain:       []string{testdata.CertFromIntermediate, testdata.IntermediateFromRoot, testdata.CACertPEM},
-			wantIdx:     0,
-			wantLogSize: 1,
-			want:        http.StatusOK,
+			descr:         "success-duplicate",
+			chain:         []string{testdata.CertFromIntermediate, testdata.IntermediateFromRoot, testdata.CACertPEM},
+			wantIdx:       0,
+			wantLogSize:   1,
+			wantTimestamp: fakeTimeStart.Add(3 * time.Minute),
+			want:          http.StatusOK,
 		},
 		{
-			descr:       "success-not-duplicate",
-			chain:       []string{testdata.TestCertPEM, testdata.CACertPEM},
-			wantIdx:     1,
-			wantLogSize: 2,
-			want:        http.StatusOK,
+			descr:         "success-not-duplicate",
+			chain:         []string{testdata.TestCertPEM, testdata.CACertPEM},
+			wantIdx:       1,
+			wantLogSize:   2,
+			wantTimestamp: fakeTimeStart.Add(5 * time.Minute),
+			want:          http.StatusOK,
 		},
 		{
-			descr:       "success-without-root",
-			chain:       []string{testdata.CertFromIntermediate, testdata.IntermediateFromRoot},
-			wantIdx:     0,
-			wantLogSize: 2,
-			want:        http.StatusOK,
+			descr:         "success-without-root-duplicate",
+			chain:         []string{testdata.CertFromIntermediate, testdata.IntermediateFromRoot},
+			wantIdx:       0,
+			wantLogSize:   2,
+			wantTimestamp: fakeTimeStart.Add(3 * time.Minute),
+			want:          http.StatusOK,
 		},
 	}
 
 	log, dir := setupTestLog(t)
 	server := setupTestServer(t, log, path.Join(prefix, rfc6962.AddChainPath))
 	defer server.Close()
+	defer timeSource.Reset()
 
 	for _, test := range tests {
+		// Increment time to make it unique for each test case.
+		timeSource.Add1m()
 		t.Run(test.descr, func(t *testing.T) {
 			pool := loadCertsIntoPoolOrDie(t, test.chain)
 			chain := createJSONChain(t, *pool)
 
 			resp, err := http.Post(server.URL+rfc6962.AddChainPath, "application/json", chain)
+
 			if err != nil {
 				t.Fatalf("http.Post(%s)=(_,%q); want (_,nil)", rfc6962.AddChainPath, err)
 			}
@@ -508,7 +533,7 @@ func TestAddChain(t *testing.T) {
 				t.Errorf("http.Post(%s)=(%d,nil); want (%d,nil)", rfc6962.AddChainPath, got, want)
 			}
 			if test.want == http.StatusOK {
-				unseqEntry, wantIssChain := parseChain(t, false, test.chain, log.chainValidator.Roots()[0])
+				unseqEntry, wantIssChain := parseChain(t, false, test.chain, log.chainValidator.Roots()[0], test.wantTimestamp)
 
 				var gotRsp rfc6962.AddChainResponse
 				if err := json.NewDecoder(resp.Body).Decode(&gotRsp); err != nil {
@@ -520,7 +545,7 @@ func TestAddChain(t *testing.T) {
 				if got, want := gotRsp.ID, demoLogID[:]; !bytes.Equal(got, want) {
 					t.Errorf("resp.ID=%v; want %v", got, want)
 				}
-				if got, want := gotRsp.Timestamp, fakeTimeMillis; got != want {
+				if got, want := gotRsp.Timestamp, uint64(test.wantTimestamp.UnixMilli()); got != want {
 					t.Errorf("resp.Timestamp=%d; want %d", got, want)
 				}
 				if got, want := hex.EncodeToString(gotRsp.Signature), "040300067369676e6564"; got != want {
@@ -583,12 +608,13 @@ func TestAddChain(t *testing.T) {
 
 func TestAddPreChain(t *testing.T) {
 	var tests = []struct {
-		descr       string
-		chain       []string
-		want        int
-		wantIdx     uint64
-		wantLogSize uint64
-		err         error
+		descr         string
+		chain         []string
+		want          int
+		wantIdx       uint64
+		wantLogSize   uint64
+		wantTimestamp time.Time
+		err           error
 	}{
 		{
 			descr: "leaf-signed-by-different",
@@ -601,40 +627,47 @@ func TestAddPreChain(t *testing.T) {
 			want:  http.StatusBadRequest,
 		},
 		{
-			descr:       "success",
-			chain:       []string{testdata.PrecertPEMValid, testdata.CACertPEM},
-			want:        http.StatusOK,
-			wantIdx:     0,
-			wantLogSize: 1,
+			descr:         "success",
+			chain:         []string{testdata.PrecertPEMValid, testdata.CACertPEM},
+			want:          http.StatusOK,
+			wantIdx:       0,
+			wantLogSize:   1,
+			wantTimestamp: fakeTimeStart.Add(3 * time.Minute),
 		},
 		{
-			descr:       "success-duplicate",
-			chain:       []string{testdata.PrecertPEMValid, testdata.CACertPEM},
-			want:        http.StatusOK,
-			wantIdx:     0,
-			wantLogSize: 1,
+			descr:         "success-duplicate",
+			chain:         []string{testdata.PrecertPEMValid, testdata.CACertPEM},
+			want:          http.StatusOK,
+			wantIdx:       0,
+			wantLogSize:   1,
+			wantTimestamp: fakeTimeStart.Add(3 * time.Minute),
 		},
 		{
-			descr:       "success-with-intermediate",
-			chain:       []string{testdata.PreCertFromIntermediate, testdata.IntermediateFromRoot, testdata.CACertPEM},
-			want:        http.StatusOK,
-			wantIdx:     1,
-			wantLogSize: 2,
+			descr:         "success-with-intermediate",
+			chain:         []string{testdata.PreCertFromIntermediate, testdata.IntermediateFromRoot, testdata.CACertPEM},
+			want:          http.StatusOK,
+			wantIdx:       1,
+			wantLogSize:   2,
+			wantTimestamp: fakeTimeStart.Add(5 * time.Minute),
 		},
 		{
-			descr:       "success-without-root",
-			chain:       []string{testdata.PrecertPEMValid},
-			want:        http.StatusOK,
-			wantIdx:     0,
-			wantLogSize: 2,
+			descr:         "success-without-root-duplicate",
+			chain:         []string{testdata.PrecertPEMValid},
+			want:          http.StatusOK,
+			wantIdx:       0,
+			wantLogSize:   2,
+			wantTimestamp: fakeTimeStart.Add(3 * time.Minute),
 		},
 	}
 
 	log, dir := setupTestLog(t)
 	server := setupTestServer(t, log, path.Join(prefix, rfc6962.AddPreChainPath))
 	defer server.Close()
+	defer timeSource.Reset()
 
 	for _, test := range tests {
+		// Increment time to make it unique for each test case.
+		timeSource.Add1m()
 		t.Run(test.descr, func(t *testing.T) {
 			pool := loadCertsIntoPoolOrDie(t, test.chain)
 			chain := createJSONChain(t, *pool)
@@ -647,7 +680,7 @@ func TestAddPreChain(t *testing.T) {
 				t.Errorf("http.Post(%s)=(%d,nil); want (%d,nil)", rfc6962.AddPreChainPath, got, want)
 			}
 			if test.want == http.StatusOK {
-				unseqEntry, wantIssChain := parseChain(t, true, test.chain, log.chainValidator.Roots()[0])
+				unseqEntry, wantIssChain := parseChain(t, true, test.chain, log.chainValidator.Roots()[0], test.wantTimestamp)
 
 				var gotRsp rfc6962.AddChainResponse
 				if err := json.NewDecoder(resp.Body).Decode(&gotRsp); err != nil {
@@ -659,7 +692,7 @@ func TestAddPreChain(t *testing.T) {
 				if got, want := gotRsp.ID, demoLogID[:]; !bytes.Equal(got, want) {
 					t.Errorf("resp.ID=%v; want %v", got, want)
 				}
-				if got, want := gotRsp.Timestamp, fakeTimeMillis; got != want {
+				if got, want := gotRsp.Timestamp, uint64(test.wantTimestamp.UnixMilli()); got != want {
 					t.Errorf("resp.Timestamp=%d; want %d", got, want)
 				}
 				if got, want := hex.EncodeToString(gotRsp.Signature), "040300067369676e6564"; got != want {
diff --git a/internal/types/staticct/staticct.go b/internal/types/staticct/staticct.go
index 5e78a897..cb08a1ad 100644
--- a/internal/types/staticct/staticct.go
+++ b/internal/types/staticct/staticct.go
@@ -37,6 +37,8 @@ type EntryBundle struct {
 
 // UnmarshalText implements encoding/TextUnmarshaler and reads EntryBundles
 // which are encoded using the Static CT API spec.
+// TODO(phbnf): we can probably parse every individual leaf directly, since most callers
+// of this method tend to do so.
 func (t *EntryBundle) UnmarshalText(raw []byte) error {
 	entries := make([][]byte, 0, layout.EntryBundleWidth)
 	s := cryptobyte.String(raw)
@@ -164,6 +166,21 @@ type Entry struct {
 	LeafIndex         uint64
 }
 
+// UnmarshalText implements encoding/TextUnmarshaler and reads EntryBundles
+// which are encoded using the Static CT API spec.
+func UnmarshalTimestamp(raw []byte) (uint64, error) {
+	s := cryptobyte.String(raw)
+	var t uint64
+
+	if !s.ReadUint64(&t) {
+		return 0, fmt.Errorf("invalid data tile: timestamp can't be extracted")
+	}
+	if t > math.MaxInt64 {
+		return 0, fmt.Errorf("invalid data tile: timestamp %d > math.MaxInt64", t)
+	}
+	return t, nil
+}
+
 // UnmarshalText implements encoding/TextUnmarshaler and reads EntryBundles
 // which are encoded using the Static CT API spec.
 func (t *Entry) UnmarshalText(raw []byte) error {
diff --git a/modules/README.md b/modules/README.md
deleted file mode 100644
index c73e698c..00000000
--- a/modules/README.md
+++ /dev/null
@@ -1,5 +0,0 @@
-# Modules
-
-This directory contains modules that Tessera Personality can link to get extra functionalities.
-
-TODO: move out of this directory once we've sorted out repo structure for personalities
\ No newline at end of file
diff --git a/modules/dedup/dedup.go b/modules/dedup/dedup.go
deleted file mode 100644
index 03a73053..00000000
--- a/modules/dedup/dedup.go
+++ /dev/null
@@ -1,167 +0,0 @@
-// Copyright 2024 The Tessera authors. All Rights Reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Package dedup limits the number of duplicate entries a personality allows in a Tessera log.
-package dedup
-
-import (
-	"bytes"
-	"context"
-	"crypto/sha256"
-	"errors"
-	"fmt"
-	"math"
-	"os"
-	"strconv"
-	"time"
-
-	"github.com/transparency-dev/trillian-tessera/api/layout"
-	"github.com/transparency-dev/trillian-tessera/client"
-	"golang.org/x/crypto/cryptobyte"
-	"k8s.io/klog/v2"
-)
-
-// LeafDedupInfo enables building deduplicated add-pre-chain/add-chain responses.
-type LeafDedupInfo struct {
-	LeafID []byte
-	SCTDedupInfo
-}
-
-// SCTDedupInfo contains data to build idempotent SCTs.
-type SCTDedupInfo struct {
-	Idx       uint64
-	Timestamp uint64
-}
-
-type BEDedupStorage interface {
-	Add(ctx context.Context, lidxs []LeafDedupInfo) error
-	Get(ctx context.Context, leafID []byte) (SCTDedupInfo, bool, error)
-}
-
-// TODO: re-architecture to prevent creating a LocaLBEDedupStorage without calling UpdateFromLog
-type LocalBEDedupStorage interface {
-	Add(ctx context.Context, lidxs []LeafDedupInfo) error
-	Get(ctx context.Context, leafID []byte) (SCTDedupInfo, bool, error)
-	LogSize() (uint64, error)
-}
-
-type ParseBundleFunc func([]byte, uint64) ([]LeafDedupInfo, error)
-
-// UpdateFromLog synchronises a local best effort deduplication storage with a log.
-func UpdateFromLog(ctx context.Context, lds LocalBEDedupStorage, t time.Duration, fcp client.CheckpointFetcherFunc, fb client.EntryBundleFetcherFunc, pb ParseBundleFunc) {
-	tck := time.NewTicker(t)
-	defer tck.Stop()
-	for {
-		select {
-		case <-ctx.Done():
-			return
-		case <-tck.C:
-			if err := sync(ctx, lds, pb, fcp, fb); err != nil {
-				klog.Warningf("error updating deduplication data: %v", err)
-			}
-		}
-	}
-}
-
-// sync synchronises a deduplication storage with the corresponding log content.
-func sync(ctx context.Context, lds LocalBEDedupStorage, pb ParseBundleFunc, fcp client.CheckpointFetcherFunc, fb client.EntryBundleFetcherFunc) error {
-	cpRaw, err := fcp(ctx)
-	if err != nil {
-		return fmt.Errorf("error fetching checkpoint: %v", err)
-	}
-	// A https://c2sp.org/static-ct-api logsize is on the second line
-	l := bytes.SplitN(cpRaw, []byte("\n"), 3)
-	if len(l) < 2 {
-		return errors.New("invalid checkpoint - no size")
-	}
-	ckptSize, err := strconv.ParseUint(string(l[1]), 10, 64)
-	if err != nil {
-		return fmt.Errorf("invalid checkpoint - can't extract size: %v", err)
-	}
-	oldSize, err := lds.LogSize()
-	if err != nil {
-		return fmt.Errorf("OldSize(): %v", err)
-	}
-
-	// TODO(phboneff): add parallelism
-	// Greatly inspired by
-	// https://github.com/transparency-dev/trillian-tessera/blob/main/client/client.go
-	if ckptSize > oldSize {
-		klog.V(2).Infof("LocalBEDEdup.sync(): log at size %d, dedup database at size %d, startig to sync", ckptSize, oldSize)
-		for i := oldSize / 256; i <= ckptSize/256; i++ {
-			eRaw, err := fb(ctx, i, layout.PartialTileSize(0, i, ckptSize))
-			if err != nil {
-				if errors.Is(err, os.ErrNotExist) {
-					return fmt.Errorf("leaf bundle at index %d not found: %v", i, err)
-				}
-				return fmt.Errorf("failed to fetch leaf bundle at index %d: %v", i, err)
-			}
-			ldis, err := pb(eRaw, i)
-			if err != nil {
-				return fmt.Errorf("parseBundle(): %v", err)
-			}
-
-			if err := lds.Add(ctx, ldis); err != nil {
-				return fmt.Errorf("error storing deduplication data for tile %d: %v", i, err)
-			}
-			klog.V(3).Infof("LocalBEDEdup.sync(): stored dedup data for entry bundle %d, %d more bundles to go", i, ckptSize/256-i)
-		}
-	}
-	klog.V(3).Infof("LocalBEDEdup.sync(): dedup data synced to logsize %d", ckptSize)
-	return nil
-}
-
-// DedupFromBundle converts a bundle into an array of LeafDedupInfo.
-//
-// The index of a leaf is computed from its position in the log, instead of parsing SCTs.
-// Greatly inspired by https://github.com/FiloSottile/sunlight/blob/main/tile.go
-// TODO(phboneff): move this somewhere else, and only leave crypto in this file
-func DedupFromBundle(bundle []byte, bundleIdx uint64) ([]LeafDedupInfo, error) {
-	kvs := []LeafDedupInfo{}
-	s := cryptobyte.String(bundle)
-
-	for i := bundleIdx * 256; len(s) > 0; i++ {
-		var timestamp uint64
-		var entryType uint16
-		var extensions, fingerprints cryptobyte.String
-		if !s.ReadUint64(&timestamp) || !s.ReadUint16(&entryType) || timestamp > math.MaxInt64 {
-			return nil, fmt.Errorf("invalid data tile")
-		}
-		crt := []byte{}
-		switch entryType {
-		case 0: // x509_entry
-			if !s.ReadUint24LengthPrefixed((*cryptobyte.String)(&crt)) ||
-				!s.ReadUint16LengthPrefixed(&extensions) ||
-				!s.ReadUint16LengthPrefixed(&fingerprints) {
-				return nil, fmt.Errorf("invalid data tile x509_entry")
-			}
-		case 1: // precert_entry
-			IssuerKeyHash := [32]byte{}
-			var defangedCrt, extensions cryptobyte.String
-			if !s.CopyBytes(IssuerKeyHash[:]) ||
-				!s.ReadUint24LengthPrefixed(&defangedCrt) ||
-				!s.ReadUint16LengthPrefixed(&extensions) ||
-				!s.ReadUint24LengthPrefixed((*cryptobyte.String)(&crt)) ||
-				!s.ReadUint16LengthPrefixed(&fingerprints) {
-				return nil, fmt.Errorf("invalid data tile precert_entry")
-			}
-		default:
-			return nil, fmt.Errorf("invalid data tile: unknown type %d", entryType)
-		}
-		k := sha256.Sum256(crt)
-		sctDedupInfo := SCTDedupInfo{Idx: uint64(i), Timestamp: timestamp}
-		kvs = append(kvs, LeafDedupInfo{LeafID: k[:], SCTDedupInfo: sctDedupInfo})
-	}
-	return kvs, nil
-}
diff --git a/storage/bbolt/dedup.go b/storage/bbolt/dedup.go
deleted file mode 100644
index 20d998e2..00000000
--- a/storage/bbolt/dedup.go
+++ /dev/null
@@ -1,228 +0,0 @@
-// Copyright 2024 The Tessera authors. All Rights Reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Package bbolt implements modules/dedup using BBolt.
-//
-// It contains two buckets:
-//   - The dedup bucket stores <leafID, {idx, timestamp}> pairs. Entries can either be added after
-//     sequencing, by the server that received the request, or later when synchronising the dedup
-//     storage with the log state.
-//   - The size bucket has a single entry: <"size", X>, where X is the largest contiguous index
-//     from 0 that has been inserted in the dedup bucket. This allows to know at what index
-//     deduplication synchronisation should start in order to have the full picture of a log.
-//
-// Calls to Add<leafID, idx> will update idx to a smaller value, if possible.
-package bbolt
-
-import (
-	"context"
-	"encoding/binary"
-	"fmt"
-
-	"github.com/transparency-dev/static-ct/modules/dedup"
-
-	bolt "go.etcd.io/bbolt"
-	"k8s.io/klog/v2"
-)
-
-var (
-	dedupBucket = "leafIdx"
-	sizeBucket  = "logSize"
-)
-
-type Storage struct {
-	db *bolt.DB
-}
-
-// NewStorage returns a new BBolt storage instance with a dedup and size bucket.
-//
-// The dedup bucket stores <leafID, {idx, timestamp}> pairs, where idx::timestamp is the
-// concatenation of two uint64 8 bytes BigEndian representation.
-// The size bucket has a single entry: <"size", X>, where X is the largest contiguous index from 0
-// that has been inserted in the dedup bucket.
-//
-// If a database already exists at the provided path, NewStorage will load it.
-func NewStorage(path string) (*Storage, error) {
-	db, err := bolt.Open(path, 0600, nil)
-	if err != nil {
-		return nil, fmt.Errorf("bolt.Open(): %v", err)
-	}
-	s := &Storage{db: db}
-
-	err = db.Update(func(tx *bolt.Tx) error {
-		dedupB := tx.Bucket([]byte(dedupBucket))
-		sizeB := tx.Bucket([]byte(sizeBucket))
-		if dedupB == nil && sizeB == nil {
-			klog.V(2).Infof("NewStorage: no pre-existing buckets, will create %q and %q.", dedupBucket, sizeBucket)
-			_, err := tx.CreateBucket([]byte(dedupBucket))
-			if err != nil {
-				return fmt.Errorf("create %q bucket: %v", dedupBucket, err)
-			}
-			sb, err := tx.CreateBucket([]byte(sizeBucket))
-			if err != nil {
-				return fmt.Errorf("create %q bucket: %v", sizeBucket, err)
-			}
-			klog.V(2).Infof("NewStorage: initializing %q with size 0.", sizeBucket)
-			err = sb.Put([]byte("size"), itob(0))
-			if err != nil {
-				return fmt.Errorf("error reading logsize: %v", err)
-			}
-		} else if dedupB == nil && sizeB != nil {
-			return fmt.Errorf("inconsistent deduplication storage state %q is nil but %q it not nil", dedupBucket, sizeBucket)
-		} else if dedupB != nil && sizeB == nil {
-			return fmt.Errorf("inconsistent deduplication storage state, %q is not nil but %q is nil", dedupBucket, sizeBucket)
-		} else {
-			klog.V(2).Infof("NewStorage: found pre-existing %q and %q buckets.", dedupBucket, sizeBucket)
-		}
-		return nil
-	})
-
-	if err != nil {
-		return nil, fmt.Errorf("error initializing buckets: %v", err)
-	}
-
-	return s, nil
-}
-
-// Add inserts entries in the dedup bucket and updates the size bucket if need be.
-//
-// If an entry already exists under a key, Add only updates the value if the new idx is smaller.
-// The context is here for consistency with interfaces, but isn't used by BBolt.
-func (s *Storage) Add(_ context.Context, ldis []dedup.LeafDedupInfo) error {
-	for _, ldi := range ldis {
-		err := s.db.Update(func(tx *bolt.Tx) error {
-			db := tx.Bucket([]byte(dedupBucket))
-			sb := tx.Bucket([]byte(sizeBucket))
-
-			sizeB := sb.Get([]byte("size"))
-			if sizeB == nil {
-				return fmt.Errorf("can't find log size in bucket %q", sizeBucket)
-			}
-			size := btoi(sizeB)
-			vB, err := vtob(ldi.Idx, ldi.Timestamp)
-			if err != nil {
-				return fmt.Errorf("vtob(): %v", err)
-			}
-
-			// old should always be 16 bytes long, but double check
-			if old := db.Get(ldi.LeafID); len(old) == 16 && btoi(old[:8]) <= ldi.Idx {
-				klog.V(3).Infof("Add(): bucket %q already contains a smaller index %d < %d for entry \"%x\", not updating", dedupBucket, btoi(old[:8]), ldi.Idx, ldi.LeafID)
-			} else if err := db.Put(ldi.LeafID, vB); err != nil {
-				return err
-			}
-			// size is a length, ldi.Idx an index, so if they're equal,
-			// ldi is a new entry.
-			if size == ldi.Idx {
-				klog.V(3).Infof("Add(): updating deduped size to %d", size+1)
-				if err := sb.Put([]byte("size"), itob(size+1)); err != nil {
-					return err
-				}
-			}
-			return nil
-		})
-		if err != nil {
-			return fmt.Errorf("db.Update(): error writing leaf index %d: err", ldi.Idx)
-		}
-	}
-	return nil
-}
-
-// Get reads entries from the dedup bucket.
-//
-// If the requested entry is missing from the bucket, returns false ("comma ok" idiom).
-// The context is here for consistency with interfaces, but isn't used by BBolt.
-func (s *Storage) Get(_ context.Context, leafID []byte) (dedup.SCTDedupInfo, bool, error) {
-	var v []byte
-	_ = s.db.View(func(tx *bolt.Tx) error {
-		b := tx.Bucket([]byte(dedupBucket))
-		if vv := b.Get(leafID); vv != nil {
-			v = make([]byte, len(vv))
-			copy(v, vv)
-		}
-		return nil
-	})
-	if v == nil {
-		return dedup.SCTDedupInfo{}, false, nil
-	}
-	idx, t, err := btov(v)
-	if err != nil {
-		return dedup.SCTDedupInfo{}, false, fmt.Errorf("btov(): %v", err)
-	}
-	return dedup.SCTDedupInfo{Idx: idx, Timestamp: t}, true, nil
-}
-
-// LogSize reads the latest entry from the size bucket.
-func (s *Storage) LogSize() (uint64, error) {
-	var size []byte
-	err := s.db.View(func(tx *bolt.Tx) error {
-		b := tx.Bucket([]byte(sizeBucket))
-		v := b.Get([]byte("size"))
-		if v != nil {
-			size = make([]byte, 8)
-			copy(size, v)
-		}
-		return nil
-	})
-	if err != nil {
-		return 0, fmt.Errorf("error reading from %q: %v", sizeBucket, err)
-	}
-	if size == nil {
-		return 0, fmt.Errorf("can't find log size in bucket %q", sizeBucket)
-	}
-	return btoi(size), nil
-}
-
-// itob returns an 8-byte big endian representation of idx.
-func itob(idx uint64) []byte {
-	return binary.BigEndian.AppendUint64(nil, idx)
-}
-
-// btoi converts a byte array to a uint64
-func btoi(b []byte) uint64 {
-	return binary.BigEndian.Uint64(b)
-}
-
-// vtob concatenates an index and timestamp values into a byte array.
-func vtob(idx uint64, timestamp uint64) ([]byte, error) {
-	b := make([]byte, 0, 16)
-	var err error
-
-	b, err = binary.Append(b, binary.BigEndian, idx)
-	if err != nil {
-		return nil, fmt.Errorf("binary.Append() could not encode idx: %v", err)
-	}
-	b, err = binary.Append(b, binary.BigEndian, timestamp)
-	if err != nil {
-		return nil, fmt.Errorf("binary.Append() could not encode timestamp: %v", err)
-	}
-
-	return b, nil
-}
-
-// btov parses a byte array into an index and timestamp values.
-func btov(b []byte) (uint64, uint64, error) {
-	var idx, timestamp uint64
-	if l := len(b); l != 16 {
-		return 0, 0, fmt.Errorf("input value is %d bytes long, expected %d", l, 16)
-	}
-	n, err := binary.Decode(b, binary.BigEndian, &idx)
-	if err != nil {
-		return 0, 0, fmt.Errorf("binary.Decode() could not decode idx: %v", err)
-	}
-	_, err = binary.Decode(b[n:], binary.BigEndian, &timestamp)
-	if err != nil {
-		return 0, 0, fmt.Errorf("binary.Decode() could not decode timestamp: %v", err)
-	}
-	return idx, timestamp, nil
-}
diff --git a/storage/gcp/dedup.go b/storage/gcp/dedup.go
deleted file mode 100644
index 36408a73..00000000
--- a/storage/gcp/dedup.go
+++ /dev/null
@@ -1,97 +0,0 @@
-// Copyright 2024 The Tessera authors. All Rights Reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package gcp
-
-import (
-	"context"
-	"fmt"
-
-	"cloud.google.com/go/spanner"
-	"cloud.google.com/go/spanner/apiv1/spannerpb"
-	"github.com/transparency-dev/static-ct/modules/dedup"
-	"google.golang.org/grpc/codes"
-)
-
-// NewDedupeStorage returns a struct which can be used to store identity -> index mappings backed
-// by Spanner.
-//
-// Note that updates to this dedup storage is logically entriely separate from any updates
-// happening to the log storage.
-func NewDedupeStorage(ctx context.Context, spannerDB string) (*DedupStorage, error) {
-	/*
-	   Schema for reference:
-
-	   	CREATE TABLE IDSeq (
-	   	 id INT64 NOT NULL,
-	   	 h BYTES(MAX) NOT NULL,
-	   	 idx INT64 NOT NULL,
-	   	 timestamp INT64 NOT NULL,
-	   	) PRIMARY KEY (id, h);
-	*/
-	dedupDB, err := spanner.NewClient(ctx, spannerDB)
-	if err != nil {
-		return nil, fmt.Errorf("failed to connect to Spanner: %v", err)
-	}
-
-	return &DedupStorage{
-		dbPool: dedupDB,
-	}, nil
-}
-
-// DedupStorage is a GCP Spanner based dedup storage implementation for TesseraCT.
-type DedupStorage struct {
-	dbPool *spanner.Client
-}
-
-var _ dedup.BEDedupStorage = &DedupStorage{}
-
-// Get looks up the stored index, if any, for the given identity.
-func (d *DedupStorage) Get(ctx context.Context, i []byte) (dedup.SCTDedupInfo, bool, error) {
-	var idx, timestamp int64
-	if row, err := d.dbPool.Single().ReadRow(ctx, "IDSeq", spanner.Key{0, i}, []string{"idx", "timestamp"}); err != nil {
-		if c := spanner.ErrCode(err); c == codes.NotFound {
-			return dedup.SCTDedupInfo{}, false, nil
-		}
-		return dedup.SCTDedupInfo{}, false, err
-	} else {
-		if err := row.Columns(&idx, &timestamp); err != nil {
-			return dedup.SCTDedupInfo{}, false, fmt.Errorf("failed to read dedup index: %v", err)
-		}
-		idx := uint64(idx)
-		t := uint64(timestamp)
-		return dedup.SCTDedupInfo{Idx: idx, Timestamp: t}, true, nil
-	}
-}
-
-// Add stores associations between the passed-in identities and their indices.
-func (d *DedupStorage) Add(ctx context.Context, entries []dedup.LeafDedupInfo) error {
-	m := make([]*spanner.MutationGroup, 0, len(entries))
-	for _, e := range entries {
-		m = append(m, &spanner.MutationGroup{
-			Mutations: []*spanner.Mutation{
-				spanner.Insert("IDSeq", []string{"id", "h", "idx", "timestamp"},
-					[]any{0, e.LeafID, int64(e.Idx), int64(e.Timestamp)})},
-		})
-	}
-
-	i := d.dbPool.BatchWrite(ctx, m)
-	return i.Do(func(r *spannerpb.BatchWriteResponse) error {
-		s := r.GetStatus()
-		if c := codes.Code(s.Code); c != codes.OK && c != codes.AlreadyExists {
-			return fmt.Errorf("failed to write dedup record: %v (%v)", s.GetMessage(), c)
-		}
-		return nil
-	})
-}
diff --git a/storage/storage.go b/storage/storage.go
index 42a620f4..c37bc883 100644
--- a/storage/storage.go
+++ b/storage/storage.go
@@ -15,15 +15,21 @@
 package storage
 
 import (
+	"bytes"
 	"context"
 	"crypto/sha256"
 	"crypto/x509"
 	"encoding/hex"
+	"errors"
 	"fmt"
+	"os"
+	"strconv"
 	"sync"
+	"time"
 
-	"github.com/transparency-dev/static-ct/modules/dedup"
+	"github.com/transparency-dev/static-ct/internal/types/staticct"
 	tessera "github.com/transparency-dev/trillian-tessera"
+	"github.com/transparency-dev/trillian-tessera/api/layout"
 	"github.com/transparency-dev/trillian-tessera/ctonly"
 	"golang.org/x/mod/sumdb/note"
 	"k8s.io/klog/v2"
@@ -49,30 +55,91 @@ type IssuerStorage interface {
 	AddIssuersIfNotExist(ctx context.Context, kv []KV) error
 }
 
-// CTStorage implements ct.Storage.
+// CTStorage implements ct.Storage and tessera.LogReader.
 type CTStorage struct {
 	storeData    func(context.Context, *ctonly.Entry) tessera.IndexFuture
 	storeIssuers func(context.Context, []KV) error
-	dedupStorage dedup.BEDedupStorage
+	reader       tessera.LogReader
+	awaiter      *tessera.PublicationAwaiter
 }
 
 // NewCTStorage instantiates a CTStorage object.
-func NewCTStorage(logStorage *tessera.Appender, issuerStorage IssuerStorage, dedupStorage dedup.BEDedupStorage) (*CTStorage, error) {
+func NewCTStorage(ctx context.Context, logStorage *tessera.Appender, issuerStorage IssuerStorage, reader tessera.LogReader) (*CTStorage, error) {
+	awaiter := tessera.NewPublicationAwaiter(ctx, reader.ReadCheckpoint, 200*time.Millisecond)
 	ctStorage := &CTStorage{
 		storeData:    tessera.NewCertificateTransparencyAppender(logStorage),
 		storeIssuers: cachedStoreIssuers(issuerStorage),
-		dedupStorage: dedupStorage,
+		reader:       reader,
+		awaiter:      awaiter,
 	}
 	return ctStorage, nil
 }
 
+func (cts *CTStorage) ReadCheckpoint(ctx context.Context) ([]byte, error) {
+	return cts.reader.ReadCheckpoint(ctx)
+}
+
+// TODO(phbnf): cache timestamps (or more) to avoid reparsing the entire leaf bundle
+func (cts *CTStorage) dedupFuture(ctx context.Context, f tessera.IndexFuture) (index, timestamp uint64, err error) {
+	ctx, span := tracer.Start(ctx, "tesseract.storage.dedupFuture")
+	defer span.End()
+
+	idx, cpRaw, err := cts.awaiter.Await(ctx, f)
+	if err != nil {
+		return 0, 0, fmt.Errorf("error waiting for Tessera future and its integration: %v", err)
+	}
+
+	// A https://c2sp.org/static-ct-api logsize is on the second line
+	l := bytes.SplitN(cpRaw, []byte("\n"), 3)
+	if len(l) < 2 {
+		return 0, 0, errors.New("invalid checkpoint - no size")
+	}
+	ckptSize, err := strconv.ParseUint(string(l[1]), 10, 64)
+	if err != nil {
+		return 0, 0, fmt.Errorf("invalid checkpoint - can't extract size: %v", err)
+	}
+
+	eBIdx := idx.Index / layout.EntryBundleWidth
+	eBRaw, err := cts.reader.ReadEntryBundle(ctx, eBIdx, layout.PartialTileSize(0, eBIdx, ckptSize))
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return 0, 0, fmt.Errorf("leaf bundle at index %d not found: %v", eBIdx, err)
+		}
+		return 0, 0, fmt.Errorf("failed to fetch entry bundle at index %d: %v", eBIdx, err)
+	}
+	eb := staticct.EntryBundle{}
+	if err := eb.UnmarshalText(eBRaw); err != nil {
+		return 0, 0, fmt.Errorf("failed to unmarshal entry bundle at index %d: %v", eBIdx, err)
+	}
+
+	eIdx := idx.Index % layout.EntryBundleWidth
+	if uint64(len(eb.Entries)) <= eIdx {
+		return 0, 0, fmt.Errorf("entry bundle at index %d has only %d entries, but wanted at least %d", eBIdx, eIdx, eBIdx)
+	}
+	e := staticct.Entry{}
+	t, err := staticct.UnmarshalTimestamp([]byte(eb.Entries[eIdx]))
+	if err != nil {
+		return 0, 0, fmt.Errorf("failed to extract timestamp from entry %d in entry bundle %d: %v", eIdx, eBIdx, e)
+	}
+
+	return idx.Index, t, nil
+}
+
 // Add stores CT entries.
-func (cts *CTStorage) Add(ctx context.Context, entry *ctonly.Entry) tessera.IndexFuture {
+func (cts *CTStorage) Add(ctx context.Context, entry *ctonly.Entry) (uint64, uint64, error) {
 	ctx, span := tracer.Start(ctx, "tesseract.storage.Add")
 	defer span.End()
 
-	// TODO(phboneff): add deduplication and chain storage
-	return cts.storeData(ctx, entry)
+	future := cts.storeData(ctx, entry)
+	idx, err := future()
+	if err != nil {
+		return 0, 0, fmt.Errorf("error waiting for Tessera future: %v", err)
+	}
+	if idx.IsDup {
+		return cts.dedupFuture(ctx, future)
+	}
+	return idx.Index, entry.Timestamp, nil
+
 }
 
 // AddIssuerChain stores every chain certificate under its sha256.
@@ -128,28 +195,3 @@ func cachedStoreIssuers(s IssuerStorage) func(context.Context, []KV) error {
 		return nil
 	}
 }
-
-// AddCertDedupInfo stores <cert_hash, SCTDedupInfo> in the deduplication storage.
-func (cts CTStorage) AddCertDedupInfo(ctx context.Context, c *x509.Certificate, sctDedupInfo dedup.SCTDedupInfo) error {
-	ctx, span := tracer.Start(ctx, "tesseract.storage.AddCertDedupInfo")
-	defer span.End()
-
-	key := sha256.Sum256(c.Raw)
-	if err := cts.dedupStorage.Add(ctx, []dedup.LeafDedupInfo{{LeafID: key[:], SCTDedupInfo: sctDedupInfo}}); err != nil {
-		return fmt.Errorf("error storing SCTDedupInfo %+v of \"%x\": %v", sctDedupInfo, key, err)
-	}
-	return nil
-}
-
-// GetCertDedupInfo fetches the SCTDedupInfo of a given certificate from the deduplication storage.
-func (cts CTStorage) GetCertDedupInfo(ctx context.Context, c *x509.Certificate) (dedup.SCTDedupInfo, bool, error) {
-	ctx, span := tracer.Start(ctx, "tesseract.storageGetCertDedupInfo")
-	defer span.End()
-
-	key := sha256.Sum256(c.Raw)
-	sctC, ok, err := cts.dedupStorage.Get(ctx, key[:])
-	if err != nil {
-		return dedup.SCTDedupInfo{}, false, fmt.Errorf("error fetching index of \"%x\": %v", key, err)
-	}
-	return sctC, ok, nil
-}