diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9ce08e1..01899a1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,28 +10,33 @@ concurrency:
   group: ci-${{ github.ref }}
   cancel-in-progress: true
 
-
 jobs:
   build:
-    runs-on: ubuntu-latest
     strategy:
-      fail-fast: true
-
+      fail-fast: false
+    runs-on: ubuntu-latest
     steps:
-    - name: Checkout
-      uses: actions/checkout@v2
-
-    - name: Cache
-      uses: coursier/cache-action@v6
-
-    - name: Setup Java
-      uses: actions/setup-java@v2
-      with:
-          distribution: adopt
-          java-version: 11
-
-    - name: Run tests
-      run: |
-        ./mill -k --disable-ticker __.resolvedIvyDeps &&
-        ./mill -k --disable-ticker mill.scalalib.scalafmt.ScalafmtModule/checkFormatAll __.sources &&
-        ./mill -j 0 -k --disable-ticker __.test
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+
+      - uses: actions/setup-java@v3
+        with:
+          distribution: "temurin"
+          java-version: "21"
+          cache: "sbt"
+
+      - name: Setup sbt
+        uses: sbt/setup-sbt@v1
+
+      - name: Test
+        run: sbt ci
+
+      - name: Publish ${{ github.ref }}
+        # if: github.event_name != 'pull_request' && (startsWith(github.ref, 'refs/tags/v') || (github.ref == 'refs/heads/main'))
+        run: sbt ci-release
+        env:
+          PGP_PASSPHRASE: ${{ secrets.PGP_PASSPHRASE }}
+          PGP_SECRET: ${{ secrets.PGP_SECRET }}
+          SONATYPE_PASSWORD: ${{ secrets.SONATYPE_PASSWORD }}
+          SONATYPE_USERNAME: ${{ secrets.SONATYPE_USERNAME }}
diff --git a/.mill-version b/.mill-version
deleted file mode 100644
index 70016a7..0000000
--- a/.mill-version
+++ /dev/null
@@ -1 +0,0 @@
-0.10.12
diff --git a/.sbtopts b/.sbtopts
new file mode 100644
index 0000000..e18f135
--- /dev/null
+++ b/.sbtopts
@@ -0,0 +1 @@
+-J-Xmx6g
diff --git a/README.md b/README.md
index 0cc4755..64acc58 100644
--- a/README.md
+++ b/README.md
@@ -38,4 +38,4 @@ override def ivyDeps = super.ivyDeps() ++ Agg(ivy"tech.neander::jsonrpclib-fs2::
 
 **/!\ Please be aware that this library is in its early days and offers strictly no guarantee with regards to backward compatibility**
 
-See the examples folder
+See the modules/examples folder.
diff --git a/build.sbt b/build.sbt
new file mode 100644
index 0000000..2568eb2
--- /dev/null
+++ b/build.sbt
@@ -0,0 +1,124 @@
+import org.typelevel.sbt.tpolecat.DevMode
+import org.typelevel.sbt.tpolecat.OptionsMode
+import java.net.URI
+
+inThisBuild(
+  List(
+    organization := "org.polyvariant",
+    homepage := Some(url("https://github.com/neandertech/jsonrpclib")),
+    licenses := List(License.Apache2),
+    developers := List(
+      Developer("Baccata", "Olivier Mélois", "baccata64@gmail.com", URI.create("https://github.com/baccata").toURL)
+    ),
+    sonatypeCredentialHost := "s01.oss.sonatype.org",
+    sonatypeRepository := "https://s01.oss.sonatype.org/service/local"
+  )
+)
+
+val scala213 = "2.13.16"
+val scala3 = "3.3.5"
+val allScalaVersions = List(scala213, scala3)
+val jvmScalaVersions = allScalaVersions
+val jsScalaVersions = allScalaVersions
+val nativeScalaVersions = allScalaVersions
+
+ThisBuild / tpolecatOptionsMode := DevMode
+
+val commonSettings = Seq(
+  libraryDependencies ++= Seq(
+    "com.disneystreaming" %%% "weaver-cats" % "0.8.4" % Test
+  ),
+  mimaPreviousArtifacts := Set(
+    "tech.neander" %%% name.value % "0.0.7"
+  ),
+  scalacOptions += "-java-output-version:8"
+)
+
+val core = projectMatrix
+  .in(file("modules") / "core")
+  .jvmPlatform(
+    jvmScalaVersions,
+    Test / unmanagedSourceDirectories ++= Seq(
+      (projectMatrixBaseDirectory.value / "src" / "test" / "scalajvm-native").getAbsoluteFile
+    )
+  )
+  .jsPlatform(jsScalaVersions)
+  .nativePlatform(
+    nativeScalaVersions,
+    Test / unmanagedSourceDirectories ++= Seq(
+      (projectMatrixBaseDirectory.value / "src" / "test" / "scalajvm-native").getAbsoluteFile
+    )
+  )
+  .disablePlugins(AssemblyPlugin)
+  .settings(
+    name := "jsonrpclib-core",
+    commonSettings,
+    libraryDependencies ++= Seq(
+      "com.github.plokhotnyuk.jsoniter-scala" %%% "jsoniter-scala-macros" % "2.30.2"
+    )
+  )
+
+val fs2 = projectMatrix
+  .in(file("modules") / "fs2")
+  .jvmPlatform(jvmScalaVersions)
+  .jsPlatform(jsScalaVersions)
+  .nativePlatform(nativeScalaVersions)
+  .disablePlugins(AssemblyPlugin)
+  .dependsOn(core)
+  .settings(
+    name := "jsonrpclib-fs2",
+    commonSettings,
+    libraryDependencies ++= Seq(
+      "co.fs2" %%% "fs2-io" % "3.12.0"
+    )
+  )
+
+val exampleServer = projectMatrix
+  .in(file("modules") / "examples/server")
+  .jvmPlatform(List(scala213))
+  .dependsOn(fs2)
+  .settings(
+    commonSettings,
+    publish / skip := true
+  )
+  .disablePlugins(MimaPlugin)
+
+val exampleClient = projectMatrix
+  .in(file("modules") / "examples/client")
+  .jvmPlatform(
+    List(scala213),
+    Seq(
+      fork := true,
+      envVars += "SERVER_JAR" -> (exampleServer.jvm(scala213) / assembly).value.toString
+    )
+  )
+  .disablePlugins(AssemblyPlugin)
+  .dependsOn(fs2)
+  .settings(
+    commonSettings,
+    publish / skip := true
+  )
+  .disablePlugins(MimaPlugin)
+
+val root = project
+  .in(file("."))
+  .settings(
+    publish / skip := true
+  )
+  .disablePlugins(MimaPlugin, AssemblyPlugin)
+  .aggregate(List(core, fs2, exampleServer, exampleClient).flatMap(_.projectRefs): _*)
+
+// The core compiles are a workaround for https://github.com/plokhotnyuk/jsoniter-scala/issues/564
+// when we switch to SN 0.5, we can use `makeWithSkipNestedOptionValues` instead: https://github.com/plokhotnyuk/jsoniter-scala/issues/564#issuecomment-2787096068
+val compileCoreModules = {
+  for {
+    scalaVersionSuffix <- List("", "3")
+    platformSuffix <- List("", "JS", "Native")
+    task <- List("compile", "package")
+  } yield s"core$platformSuffix$scalaVersionSuffix/$task"
+}.mkString(";")
+
+addCommandAlias(
+  "ci",
+  s"$compileCoreModules;test;scalafmtCheckAll;mimaReportBinaryIssues"
+)
diff --git a/build.sc b/build.sc
deleted file mode 100644
index 4b65eea..0000000
--- a/build.sc
+++ /dev/null
@@ -1,312 +0,0 @@
-import mill.define.Target
-import mill.util.Jvm
-import $ivy.`com.lihaoyi::mill-contrib-bloop:$MILL_VERSION`
-import $ivy.`io.github.davidgregory084::mill-tpolecat::0.3.5`
-import $ivy.`io.chris-kipp::mill-ci-release::0.1.9`
-
-import os.Path
-import mill._
-import scalalib._
-import publish._
-import scalajslib._
-import scalanativelib._
-import mill.scalajslib.api._
-import io.github.davidgregory084._
-import io.kipp.mill.ci.release.CiReleaseModule
-
-object versions {
-  val scala212Version = "2.12.1"
-  val scala213Version = "2.13.11"
-  val scala3Version = "3.3.3"
-  val scalaJSVersion = "1.14.0"
-  val scalaNativeVersion = "0.4.17"
-  val munitVersion = "1.0.0-M9"
-  val fs2Version = "3.10.0"
-  val weaverVersion = "0.8.3"
-  val jsoniterVersion = "2.17.0"
-
-  val scala213 = "2.13"
-  val scala212 = "2.12"
-  val scala3 = "3"
-
-  val crossMap = Map(
-    "2.13" -> scala213Version,
-    "2.12" -> scala212Version,
-    "3" -> scala3Version
-  )
-}
-import versions._
-
-object core extends RPCCrossPlatformModule { cross =>
-
-  def crossPlatformIvyDeps: T[Agg[Dep]] = Agg(
-    ivy"com.github.plokhotnyuk.jsoniter-scala::jsoniter-scala-macros::${jsoniterVersion}"
-  )
-
-  object jvm extends mill.Cross[JvmModule](scala213, scala3)
-  class JvmModule(cv: String) extends cross.JVM(cv) {
-    object test extends MunitTests
-  }
-
-  object js extends mill.Cross[JsModule](scala213, scala3)
-  class JsModule(cv: String) extends cross.JS(cv) {
-    object test extends MunitTests
-  }
-
-  object native extends mill.Cross[NativeModule](scala213, scala3)
-  class NativeModule(cv: String) extends cross.Native(cv) {
-    object test extends MunitTests
-  }
-}
-
-object fs2 extends RPCCrossPlatformModule { cross =>
-
-  override def crossPlatformModuleDeps = Seq(core)
-  def crossPlatformIvyDeps: T[Agg[Dep]] = Agg(
-    ivy"co.fs2::fs2-core::${fs2Version}"
-  )
-
-  object jvm extends mill.Cross[JvmModule](scala213, scala3)
-  class JvmModule(cv: String) extends cross.JVM(cv) {
-    object test extends WeaverTests
-  }
-
-  object js extends mill.Cross[JsModule](scala213, scala3)
-  class JsModule(cv: String) extends cross.JS(cv) {
-    object test extends WeaverTests
-  }
-
-  object native extends mill.Cross[NativeModule](scala213, scala3)
-  class NativeModule(cv: String) extends cross.Native(cv) {
-    object test extends WeaverTests
-  }
-
-}
-
-object examples extends mill.define.Module {
-
-  object server extends ScalaModule {
-    def ivyDeps = Agg(ivy"co.fs2::fs2-io:${fs2Version}")
-    def moduleDeps = Seq(fs2.jvm(versions.scala213))
-    def scalaVersion = versions.scala213Version
-  }
-
-  object client extends ScalaModule {
-    def ivyDeps = Agg(ivy"co.fs2::fs2-io:$fs2Version")
-    def moduleDeps = Seq(fs2.jvm(versions.scala213))
-    def scalaVersion = versions.scala213Version
-    def forkEnv: Target[Map[String, String]] = T {
-      val assembledServer = server.assembly()
-      super.forkEnv() ++ Map("SERVER_JAR" -> assembledServer.path.toString())
-    }
-  }
-
-}
-
-// #############################################################################
-//  COMMON SETUP
-// #############################################################################
-
-trait RPCCrossPlatformModule extends Module { shared =>
-
-  def artifactName = s"jsonrpclib-${millModuleSegments.parts.mkString("-")}"
-  def crossPlatformIvyDeps = T { Agg.empty[Dep] }
-  def crossPlatformModuleDeps: Seq[Module] = Seq()
-  def crossPlatformTestModuleDeps: Seq[Module] = Seq()
-
-  class JVM(val crossVersion: String) extends PlatformSpecific {
-    override def platformLabel: String = "jvm"
-
-    trait WeaverTests extends Tests {
-      def ivyDeps = super.ivyDeps() ++ Agg(ivy"com.disneystreaming::weaver-cats::$weaverVersion")
-      def testFramework = "weaver.framework.CatsEffect"
-    }
-
-    trait MunitTests extends Tests with TestModule.Munit {
-      def ivyDeps = super.ivyDeps() ++ Agg(ivy"org.scalameta::munit::$munitVersion")
-    }
-
-    trait Tests extends super.Tests {
-      override def sources = T.sources(computeSources(this).map(PathRef(_)))
-      override def moduleDeps = super.moduleDeps ++ shared.crossPlatformTestModuleDeps.flatMap(matchingCross)
-    }
-  }
-
-  class JS(val crossVersion: String) extends PlatformSpecific with ScalaJSModule {
-    override def platformLabel: String = "js"
-    override def scalaJSVersion = versions.scalaJSVersion
-
-    override def scalacOptions = T {
-      super.scalacOptions().filterNot(_ == "-Ywarn-unused:params")
-    }
-
-    override def moduleKind = T(ModuleKind.CommonJSModule)
-    override def skipIdea = true
-
-    trait WeaverTests extends Tests {
-      def ivyDeps = super.ivyDeps() ++ Agg(ivy"com.disneystreaming::weaver-cats::$weaverVersion")
-      def testFramework = "weaver.framework.CatsEffect"
-    }
-
-    trait MunitTests extends Tests with TestModule.Munit {
-      def ivyDeps = super.ivyDeps() ++ Agg(ivy"org.scalameta::munit::$munitVersion")
-    }
-
-    trait Tests extends super.Tests with mill.contrib.Bloop.Module {
-      override def sources = T.sources(computeSources(this).map(PathRef(_)))
-      override def skipIdea = true
-      override def skipBloop = true
-      override def moduleDeps = super.moduleDeps ++ shared.crossPlatformTestModuleDeps.flatMap(matchingCross).collect {
-        case m: ScalaJSModule => m
-      }
-    }
-  }
-
-  class Native(val crossVersion: String) extends PlatformSpecific with ScalaNativeModule {
-    override def platformLabel: String = "native"
-    override def scalaNativeVersion = versions.scalaNativeVersion
-    override def scalacOptions = T {
-      super
-        .scalacOptions()
-        .filterNot { opts =>
-          Seq(
-            "-Ywarn-extra-implicit",
-            "-Xlint:constant"
-          ).contains(opts)
-        }
-        .filterNot(_.startsWith("-Ywarn-unused"))
-    }
-    override def skipIdea = true
-    override def skipBloop = true
-
-    trait WeaverTests extends Tests {
-      def ivyDeps = super.ivyDeps() ++ Agg(ivy"com.disneystreaming::weaver-cats::$weaverVersion")
-      def testFramework = "weaver.framework.CatsEffect"
-    }
-
-    trait MunitTests extends Tests with TestModule.Munit {
-      def ivyDeps = super.ivyDeps() ++ Agg(ivy"org.scalameta::munit::$munitVersion")
-    }
-
-    trait Tests extends super.Tests with mill.contrib.Bloop.Module {
-      override def nativeLinkStubs = true
-      override def skipIdea = true
-      override def skipBloop = true
-      override def sources = T.sources(computeSources(this).map(PathRef(_)))
-      override def moduleDeps = super.moduleDeps ++ shared.crossPlatformTestModuleDeps.flatMap(matchingCross).collect {
-        case m: ScalaNativeModule => m
-      }
-    }
-  }
-
-  trait PlatformSpecific extends JsonRPCModule with mill.contrib.Bloop.Module { self =>
-    def platformLabel: String
-    def crossVersion: String
-    override def scalaVersion = versions.crossMap(crossVersion)
-
-    override def millSourcePath = shared.millSourcePath
-
-    override def ivyDeps = super.ivyDeps() ++ shared.crossPlatformIvyDeps()
-
-    def samePlatform(module: Module): Boolean =
-      self match {
-        case _: ScalaJSModule     => module.isInstanceOf[ScalaJSModule]
-        case _: ScalaNativeModule => module.isInstanceOf[ScalaNativeModule]
-        case _ =>
-          !(module.isInstanceOf[ScalaJSModule] || module
-            .isInstanceOf[ScalaNativeModule])
-      }
-
-    def sameScalaVersion(module: Module): Boolean = {
-      // Don't know why, pattern matching didn't seem to work here
-      module.isInstanceOf[PlatformSpecific] && (module.asInstanceOf[PlatformSpecific].crossVersion == self.crossVersion)
-    }
-
-    def sameCross(module: Module) = samePlatform(module) && sameScalaVersion(module)
-
-    def matchingCross(module: Module): Seq[JsonRPCModule] = module match {
-      case m: RPCCrossPlatformModule =>
-        m.millModuleDirectChildren.collect {
-          case cross: Cross[_] =>
-            cross.millModuleDirectChildren.collect {
-              case child: JsonRPCModule if sameCross(child) => child
-            }
-          case child: JsonRPCModule if sameCross(child) => Seq(child)
-        }.flatten
-      case _ => Seq()
-    }
-
-    override def moduleDeps: Seq[JsonRPCModule] =
-      shared.crossPlatformModuleDeps.flatMap(matchingCross)
-
-    override def artifactName = shared.artifactName
-
-    def computeSources(module: mill.define.Module): Seq[os.Path] = {
-      val modulePath = module.millSourcePath
-      module match {
-        case _: ScalaJSModule =>
-          Seq(
-            modulePath / 'src,
-            modulePath / s"src-js",
-            modulePath / s"src-jvm-js",
-            modulePath / s"src-js-native"
-          )
-        case _: ScalaNativeModule =>
-          Seq(
-            modulePath / 'src,
-            modulePath / s"src-native",
-            modulePath / s"src-jvm-native",
-            modulePath / s"src-js-native"
-          )
-        case _ =>
-          Seq(
-            modulePath / 'src,
-            modulePath / s"src-jvm",
-            modulePath / s"src-jvm-js",
-            modulePath / s"src-jvm-native"
-          )
-      }
-    }
-
-    override def sources = T.sources(computeSources(self).map(PathRef(_)))
-
-    override def skipBloop = {
-      self match {
-        case _: ScalaJSModule     => true
-        case _: ScalaNativeModule => true
-        case _                    => false
-      }
-    } && { crossVersion != scala213 }
-
-  }
-}
-
-trait JsonRPCModule extends ScalaModule with CiReleaseModule with scalafmt.ScalafmtModule {
-  def scalafmt() = T.command(reformat())
-  def fmt() = T.command(reformat())
-  def refreshedEnv = T.input(T.ctx().env)
-  def publishVersion = T {
-    if (refreshedEnv().contains("CI")) super.publishVersion()
-    else "dev"
-  }
-  override def scalacOptions = T {
-    super.scalacOptions() ++ Tpolecat.scalacOptionsFor(scalaVersion())
-  }
-
-  override def forkEnv = T { refreshedEnv() }
-
-  def pomSettings = PomSettings(
-    description = "A Scala jsonrpc library",
-    organization = "tech.neander",
-    url = "https://github.com/neandertech/jsonrpclib",
-    licenses = Seq(License.`Apache-2.0`),
-    versionControl = VersionControl(Some("https://github.com/neandertech/jsonrpclib")),
-    developers = Seq(
-      Developer("Baccata", "Olivier Mélois", "https://github.com/baccata")
-    )
-  )
-
-  override def sonatypeUri = "https://s01.oss.sonatype.org/service/local"
-  override def sonatypeSnapshotUri =
-    "https://s01.oss.sonatype.org/content/repositories/snapshots"
-}
diff --git a/core/test/src-jvm-native/jsonrpclib/CallIdSpec.scala b/core/test/src-jvm-native/jsonrpclib/CallIdSpec.scala
deleted file mode 100644
index 279b161..0000000
--- a/core/test/src-jvm-native/jsonrpclib/CallIdSpec.scala
+++ /dev/null
@@ -1,20 +0,0 @@
-package jsonrpclib
-
-import munit._
-import com.github.plokhotnyuk.jsoniter_scala.core._
-
-class CallIdSpec() extends FunSuite {
-  test("json parsing") {
-    val strJson = """ "25" """.trim
-    assertEquals(readFromString[CallId](strJson), CallId.StringId("25"))
-
-    val intJson = "25"
-    assertEquals(readFromString[CallId](intJson), CallId.NumberId(25))
-
-    val longJson = Long.MaxValue.toString
-    assertEquals(readFromString[CallId](longJson), CallId.NumberId(Long.MaxValue))
-
-    val nullJson = "null"
-    assertEquals(readFromString[CallId](nullJson), CallId.NullId)
-  }
-}
diff --git a/examples/client/src/examples/client/ChildProcess.scala b/examples/client/src/examples/client/ChildProcess.scala
deleted file mode 100644
index 4daaa33..0000000
--- a/examples/client/src/examples/client/ChildProcess.scala
+++ /dev/null
@@ -1,68 +0,0 @@
-package examples.client
-
-import fs2.Stream
-import cats.effect._
-import cats.syntax.all._
-import scala.jdk.CollectionConverters._
-import java.io.OutputStream
-
-trait ChildProcess[F[_]] {
-  def stdin: fs2.Pipe[F, Byte, Unit]
-  def stdout: Stream[F, Byte]
-  def stderr: Stream[F, Byte]
-}
-
-object ChildProcess {
-
-  def spawn[F[_]: Async](command: String*): Stream[F, ChildProcess[F]] =
-    Stream.bracket(start[F](command))(_._2).map(_._1)
-
-  val readBufferSize = 512
-  private def start[F[_]: Async](command: Seq[String]) = Async[F].interruptible {
-    val p =
-      new java.lang.ProcessBuilder(command.asJava)
-        .start() // .directory(new java.io.File(wd)).start()
-    val done = Async[F].fromCompletableFuture(Sync[F].delay(p.onExit()))
-
-    val terminate: F[Unit] = Sync[F].interruptible(p.destroy())
-
-    import cats._
-    val onGlobal = new (F ~> F) {
-      def apply[A](fa: F[A]): F[A] = Async[F].evalOn(fa, scala.concurrent.ExecutionContext.global)
-    }
-
-    val cp = new ChildProcess[F] {
-      def stdin: fs2.Pipe[F, Byte, Unit] =
-        writeOutputStreamFlushingChunks[F](Sync[F].interruptible(p.getOutputStream()))
-
-      def stdout: fs2.Stream[F, Byte] = fs2.io
-        .readInputStream[F](Sync[F].interruptible(p.getInputStream()), chunkSize = readBufferSize)
-        .translate(onGlobal)
-
-      def stderr: fs2.Stream[F, Byte] = fs2.io
-        .readInputStream[F](Sync[F].blocking(p.getErrorStream()), chunkSize = readBufferSize)
-        .translate(onGlobal)
-        // Avoids broken pipe - we cut off when the program ends.
-        // Users can decide what to do with the error logs using the exitCode value
-        .interruptWhen(done.void.attempt)
-    }
-    (cp, terminate)
-  }
-
-  /** Adds a flush after each chunk
-    */
-  def writeOutputStreamFlushingChunks[F[_]](
-      fos: F[OutputStream],
-      closeAfterUse: Boolean = true
-  )(implicit F: Sync[F]): fs2.Pipe[F, Byte, Nothing] =
-    s => {
-      def useOs(os: OutputStream): Stream[F, Nothing] =
-        s.chunks.foreach(c => F.interruptible(os.write(c.toArray)) >> F.blocking(os.flush()))
-
-      val os =
-        if (closeAfterUse) Stream.bracket(fos)(os => F.blocking(os.close()))
-        else Stream.eval(fos)
-      os.flatMap(os => useOs(os) ++ Stream.exec(F.blocking(os.flush())))
-    }
-
-}
diff --git a/mill b/mill
deleted file mode 100755
index 4f19f39..0000000
--- a/mill
+++ /dev/null
@@ -1,49 +0,0 @@
-#!/usr/bin/env sh
-
-# This is a wrapper script, that automatically download mill from GitHub release pages
-# You can give the required mill version with MILL_VERSION env variable
-# If no version is given, it falls back to the value of DEFAULT_MILL_VERSION
-DEFAULT_MILL_VERSION=0.10.12
-
-set -e
-
-if [ -z "$MILL_VERSION" ] ; then
-  if [ -f ".mill-version" ] ; then
-    MILL_VERSION="$(head -n 1 .mill-version 2> /dev/null)"
-  elif [ -f "mill" ] && [ "$0" != "mill" ] ; then
-    MILL_VERSION=$(grep -F "DEFAULT_MILL_VERSION=" "mill" | head -n 1 | cut -d= -f2)
-  else
-    MILL_VERSION=$DEFAULT_MILL_VERSION
-  fi
-fi
-
-if [ "x${XDG_CACHE_HOME}" != "x" ] ; then
-  MILL_DOWNLOAD_PATH="${XDG_CACHE_HOME}/mill/download"
-else
-  MILL_DOWNLOAD_PATH="${HOME}/.cache/mill/download"
-fi
-MILL_EXEC_PATH="${MILL_DOWNLOAD_PATH}/${MILL_VERSION}"
-
-version_remainder="$MILL_VERSION"
-MILL_MAJOR_VERSION="${version_remainder%%.*}"; version_remainder="${version_remainder#*.}"
-MILL_MINOR_VERSION="${version_remainder%%.*}"; version_remainder="${version_remainder#*.}"
-
-if [ ! -s "$MILL_EXEC_PATH" ] ; then
-  mkdir -p "$MILL_DOWNLOAD_PATH"
-  if [ "$MILL_MAJOR_VERSION" -gt 0 ] || [ "$MILL_MINOR_VERSION" -ge 5 ] ; then
-    ASSEMBLY="-assembly"
-  fi
-  DOWNLOAD_FILE=$MILL_EXEC_PATH-tmp-download
-  MILL_VERSION_TAG=$(echo $MILL_VERSION | sed -E 's/([^-]+)(-M[0-9]+)?(-.*)?/\1\2/')
-  MILL_DOWNLOAD_URL="https://github.com/lihaoyi/mill/releases/download/${MILL_VERSION_TAG}/$MILL_VERSION${ASSEMBLY}"
-  curl --fail -L -o "$DOWNLOAD_FILE" "$MILL_DOWNLOAD_URL"
-  chmod +x "$DOWNLOAD_FILE"
-  mv "$DOWNLOAD_FILE" "$MILL_EXEC_PATH"
-  unset DOWNLOAD_FILE
-  unset MILL_DOWNLOAD_URL
-fi
-
-unset MILL_DOWNLOAD_PATH
-unset MILL_VERSION
-
-exec $MILL_EXEC_PATH "$@"
diff --git a/core/src/jsonrpclib/CallId.scala b/modules/core/src/main/scala/jsonrpclib/CallId.scala
similarity index 100%
rename from core/src/jsonrpclib/CallId.scala
rename to modules/core/src/main/scala/jsonrpclib/CallId.scala
diff --git a/core/src/jsonrpclib/Channel.scala b/modules/core/src/main/scala/jsonrpclib/Channel.scala
similarity index 100%
rename from core/src/jsonrpclib/Channel.scala
rename to modules/core/src/main/scala/jsonrpclib/Channel.scala
diff --git a/core/src/jsonrpclib/Codec.scala b/modules/core/src/main/scala/jsonrpclib/Codec.scala
similarity index 97%
rename from core/src/jsonrpclib/Codec.scala
rename to modules/core/src/main/scala/jsonrpclib/Codec.scala
index 3f7ada7..1cc3059 100644
--- a/core/src/jsonrpclib/Codec.scala
+++ b/modules/core/src/main/scala/jsonrpclib/Codec.scala
@@ -1,7 +1,6 @@
 package jsonrpclib
 
 import com.github.plokhotnyuk.jsoniter_scala.core._
-import jsonrpclib.Payload
 
 trait Codec[A] {
 
diff --git a/core/src/jsonrpclib/ConflictingMethodError.scala b/modules/core/src/main/scala/jsonrpclib/ConflictingMethodError.scala
similarity index 100%
rename from core/src/jsonrpclib/ConflictingMethodError.scala
rename to modules/core/src/main/scala/jsonrpclib/ConflictingMethodError.scala
diff --git a/core/src/jsonrpclib/Endpoint.scala b/modules/core/src/main/scala/jsonrpclib/Endpoint.scala
similarity index 100%
rename from core/src/jsonrpclib/Endpoint.scala
rename to modules/core/src/main/scala/jsonrpclib/Endpoint.scala
diff --git a/core/src/jsonrpclib/ErrorCodec.scala b/modules/core/src/main/scala/jsonrpclib/ErrorCodec.scala
similarity index 100%
rename from core/src/jsonrpclib/ErrorCodec.scala
rename to modules/core/src/main/scala/jsonrpclib/ErrorCodec.scala
diff --git a/core/src/jsonrpclib/ErrorPayload.scala b/modules/core/src/main/scala/jsonrpclib/ErrorPayload.scala
similarity index 100%
rename from core/src/jsonrpclib/ErrorPayload.scala
rename to modules/core/src/main/scala/jsonrpclib/ErrorPayload.scala
diff --git a/core/src/jsonrpclib/ErrorReport.scala b/modules/core/src/main/scala/jsonrpclib/ErrorReport.scala
similarity index 100%
rename from core/src/jsonrpclib/ErrorReport.scala
rename to modules/core/src/main/scala/jsonrpclib/ErrorReport.scala
diff --git a/core/src/jsonrpclib/Message.scala b/modules/core/src/main/scala/jsonrpclib/Message.scala
similarity index 100%
rename from core/src/jsonrpclib/Message.scala
rename to modules/core/src/main/scala/jsonrpclib/Message.scala
diff --git a/core/src/jsonrpclib/Monadic.scala b/modules/core/src/main/scala/jsonrpclib/Monadic.scala
similarity index 100%
rename from core/src/jsonrpclib/Monadic.scala
rename to modules/core/src/main/scala/jsonrpclib/Monadic.scala
diff --git a/core/src/jsonrpclib/Payload.scala b/modules/core/src/main/scala/jsonrpclib/Payload.scala
similarity index 100%
rename from core/src/jsonrpclib/Payload.scala
rename to modules/core/src/main/scala/jsonrpclib/Payload.scala
diff --git a/core/src/jsonrpclib/ProtocolError.scala b/modules/core/src/main/scala/jsonrpclib/ProtocolError.scala
similarity index 100%
rename from core/src/jsonrpclib/ProtocolError.scala
rename to modules/core/src/main/scala/jsonrpclib/ProtocolError.scala
diff --git a/core/src/jsonrpclib/StubTemplate.scala b/modules/core/src/main/scala/jsonrpclib/StubTemplate.scala
similarity index 100%
rename from core/src/jsonrpclib/StubTemplate.scala
rename to modules/core/src/main/scala/jsonrpclib/StubTemplate.scala
diff --git a/core/src/jsonrpclib/internals/Constants.scala b/modules/core/src/main/scala/jsonrpclib/internals/Constants.scala
similarity index 100%
rename from core/src/jsonrpclib/internals/Constants.scala
rename to modules/core/src/main/scala/jsonrpclib/internals/Constants.scala
diff --git a/core/src/jsonrpclib/internals/FutureBaseChannel.scala b/modules/core/src/main/scala/jsonrpclib/internals/FutureBaseChannel.scala
similarity index 100%
rename from core/src/jsonrpclib/internals/FutureBaseChannel.scala
rename to modules/core/src/main/scala/jsonrpclib/internals/FutureBaseChannel.scala
diff --git a/core/src/jsonrpclib/internals/LSPHeaders.scala b/modules/core/src/main/scala/jsonrpclib/internals/LSPHeaders.scala
similarity index 98%
rename from core/src/jsonrpclib/internals/LSPHeaders.scala
rename to modules/core/src/main/scala/jsonrpclib/internals/LSPHeaders.scala
index 84699bb..ecc32d3 100644
--- a/core/src/jsonrpclib/internals/LSPHeaders.scala
+++ b/modules/core/src/main/scala/jsonrpclib/internals/LSPHeaders.scala
@@ -66,6 +66,7 @@ private[jsonrpclib] object LSPHeaders {
     case s"Content-type: ${mimeType}; charset=${charset}" =>
       headerBuilder.mimeType = mimeType;
       headerBuilder.charset = charset
+    case _ => sys.error(s"Invalid header: $line")
   }
 
   object integer {
diff --git a/core/src/jsonrpclib/internals/MessageDispatcher.scala b/modules/core/src/main/scala/jsonrpclib/internals/MessageDispatcher.scala
similarity index 100%
rename from core/src/jsonrpclib/internals/MessageDispatcher.scala
rename to modules/core/src/main/scala/jsonrpclib/internals/MessageDispatcher.scala
diff --git a/core/src/jsonrpclib/internals/RawMessage.scala b/modules/core/src/main/scala/jsonrpclib/internals/RawMessage.scala
similarity index 100%
rename from core/src/jsonrpclib/internals/RawMessage.scala
rename to modules/core/src/main/scala/jsonrpclib/internals/RawMessage.scala
diff --git a/core/src/jsonrpclib/package.scala b/modules/core/src/main/scala/jsonrpclib/package.scala
similarity index 100%
rename from core/src/jsonrpclib/package.scala
rename to modules/core/src/main/scala/jsonrpclib/package.scala
diff --git a/modules/core/src/test/scala/jsonrpclib/CallIdSpec.scala b/modules/core/src/test/scala/jsonrpclib/CallIdSpec.scala
new file mode 100644
index 0000000..b227173
--- /dev/null
+++ b/modules/core/src/test/scala/jsonrpclib/CallIdSpec.scala
@@ -0,0 +1,20 @@
+package jsonrpclib
+
+import weaver._
+import com.github.plokhotnyuk.jsoniter_scala.core._
+
+object CallIdSpec extends FunSuite {
+  test("json parsing") {
+    val strJson = """ "25" """.trim
+
+    val intJson = "25"
+
+    val longJson = Long.MaxValue.toString
+
+    val nullJson = "null"
+    assert.same(readFromString[CallId](strJson), CallId.StringId("25")) &&
+    assert.same(readFromString[CallId](intJson), CallId.NumberId(25)) &&
+    assert.same(readFromString[CallId](longJson), CallId.NumberId(Long.MaxValue)) &&
+    assert.same(readFromString[CallId](nullJson), CallId.NullId)
+  }
+}
diff --git a/core/test/src-jvm-native/jsonrpclib/RawMessageSpec.scala b/modules/core/src/test/scala/jsonrpclib/RawMessageSpec.scala
similarity index 77%
rename from core/test/src-jvm-native/jsonrpclib/RawMessageSpec.scala
rename to modules/core/src/test/scala/jsonrpclib/RawMessageSpec.scala
index 21a0760..be5e41a 100644
--- a/core/test/src-jvm-native/jsonrpclib/RawMessageSpec.scala
+++ b/modules/core/src/test/scala/jsonrpclib/RawMessageSpec.scala
@@ -1,30 +1,29 @@
 package jsonrpclib
 
-import munit._
+import weaver._
+import jsonrpclib.internals._
 import com.github.plokhotnyuk.jsoniter_scala.core._
-import internals._
 import jsonrpclib.CallId.NumberId
 import jsonrpclib.OutputMessage.ResponseMessage
 
-class RawMessageSpec() extends FunSuite {
+object RawMessageSpec extends FunSuite {
   test("json parsing with null result") {
     // This is a perfectly valid response object, as result field has to be present,
     // but can be null: https://www.jsonrpc.org/specification#response_object
     val rawMessage = readFromString[RawMessage](""" {"jsonrpc":"2.0","result":null,"id":3} """.trim)
-    assertEquals(
-      rawMessage,
-      RawMessage(jsonrpc = "2.0", result = Some(None), id = Some(NumberId(3)))
-    )
-
-    assertEquals(rawMessage.toMessage, Right(ResponseMessage(NumberId(3), Payload.NullPayload)))
 
     // This, on the other hand, is an invalid response message, as result field is missing
     val invalidRawMessage = readFromString[RawMessage](""" {"jsonrpc":"2.0","id":3} """.trim)
-    assertEquals(
+
+    assert.same(
+      rawMessage,
+      RawMessage(jsonrpc = "2.0", result = Some(None), id = Some(NumberId(3)))
+    ) &&
+    assert.same(rawMessage.toMessage, Right(ResponseMessage(NumberId(3), Payload.NullPayload))) &&
+    assert.same(
       invalidRawMessage,
       RawMessage(jsonrpc = "2.0", result = None, id = Some(NumberId(3)))
-    )
-
-    assert(invalidRawMessage.toMessage.isLeft, invalidRawMessage.toMessage)
+    ) &&
+    assert(invalidRawMessage.toMessage.isLeft, invalidRawMessage.toMessage.toString)
   }
 }
diff --git a/core/test/src-jvm-native/jsonrpclib/internals/HeaderSpec.scala b/modules/core/src/test/scalajvm-native/jsonrpclib/internals/HeaderSpec.scala
similarity index 91%
rename from core/test/src-jvm-native/jsonrpclib/internals/HeaderSpec.scala
rename to modules/core/src/test/scalajvm-native/jsonrpclib/internals/HeaderSpec.scala
index 4ae1f6a..e58bd59 100644
--- a/core/test/src-jvm-native/jsonrpclib/internals/HeaderSpec.scala
+++ b/modules/core/src/test/scalajvm-native/jsonrpclib/internals/HeaderSpec.scala
@@ -1,6 +1,6 @@
 package jsonrpclib.internals
 
-import munit.FunSuite
+import weaver._
 import java.io.ByteArrayInputStream
 import java.io.BufferedReader
 import java.io.InputStreamReader
@@ -8,8 +8,7 @@ import jsonrpclib.ProtocolError
 import java.io.IOException
 import java.io.UncheckedIOException
 
-class HeaderSpec() extends FunSuite {
-
+object HeaderSpec extends FunSuite {
   test("headers (all)") {
     val result = read(
       "Content-Length: 123\r",
@@ -18,7 +17,7 @@ class HeaderSpec() extends FunSuite {
       "foo..."
     )
     val expected = Result(LSPHeaders(123, "application/vscode-jsonrpc", "utf-8"), "foo...")
-    assertEquals(result, Right(expected))
+    assert.same(result, Right(expected))
   }
 
   test("headers (only content-)") {
@@ -28,7 +27,7 @@ class HeaderSpec() extends FunSuite {
       "foo..."
     )
     val expected = Result(LSPHeaders(123, "application/json", "UTF-8"), "foo...")
-    assertEquals(result, Right(expected))
+    assert.same(result, Right(expected))
   }
 
   test("no header)") {
@@ -36,7 +35,7 @@ class HeaderSpec() extends FunSuite {
       "foo"
     )
     val expected = ProtocolError.ParseError("Could not parse LSP headers")
-    assertEquals(result, Left(expected))
+    assert.same(result, Left(expected))
   }
 
   test("missing content-length") {
@@ -46,7 +45,7 @@ class HeaderSpec() extends FunSuite {
       "foo..."
     )
     val expected = ProtocolError.ParseError("Missing Content-Length header")
-    assertEquals(result, Left(expected))
+    assert.same(result, Left(expected))
   }
 
   case class Result(header: LSPHeaders, rest: String)
diff --git a/examples/client/src/examples/client/ClientMain.scala b/modules/examples/client/src/main/scala/examples/client/ClientMain.scala
similarity index 84%
rename from examples/client/src/examples/client/ClientMain.scala
rename to modules/examples/client/src/main/scala/examples/client/ClientMain.scala
index 7c87505..5097f2d 100644
--- a/examples/client/src/examples/client/ClientMain.scala
+++ b/modules/examples/client/src/main/scala/examples/client/ClientMain.scala
@@ -1,20 +1,14 @@
-package examples.server
+package examples.client
 
-import jsonrpclib.CallId
-import jsonrpclib.fs2._
 import cats.effect._
-import fs2.io._
+import cats.syntax.all._
 import com.github.plokhotnyuk.jsoniter_scala.core.JsonValueCodec
 import com.github.plokhotnyuk.jsoniter_scala.macros.JsonCodecMaker
-import jsonrpclib.Endpoint
-import cats.syntax.all._
 import fs2.Stream
-import jsonrpclib.StubTemplate
-import cats.effect.std.Dispatcher
-import cats.effect.implicits._
-import java.io.OutputStream
-import java.io.InputStream
-import examples.client.ChildProcess
+import fs2.io._
+import fs2.io.process.Processes
+import jsonrpclib.CallId
+import jsonrpclib.fs2._
 
 object ClientMain extends IOApp.Simple {
 
@@ -31,13 +25,12 @@ object ClientMain extends IOApp.Simple {
   def log(str: String): IOStream[Unit] = Stream.eval(IO.consoleForIO.errorln(str))
 
   def run: IO[Unit] = {
-    import scala.concurrent.duration._
     // Using errorln as stdout is used by the RPC channel
     val run = for {
       _ <- log("Starting client")
       serverJar <- sys.env.get("SERVER_JAR").liftTo[IOStream](new Exception("SERVER_JAR env var does not exist"))
       // Starting the server
-      rp <- ChildProcess.spawn[IO]("java", "-jar", serverJar)
+      rp <- fs2.Stream.resource(Processes[IO].spawn(process.ProcessBuilder("java", "-jar", serverJar)))
       // Creating a channel that will be used to communicate to the server
       fs2Channel <- FS2Channel[IO](cancelTemplate = cancelEndpoint.some)
       _ <- Stream(())
diff --git a/examples/server/src/examples/server/ServerMain.scala b/modules/examples/server/src/main/scala/examples/server/ServerMain.scala
similarity index 98%
rename from examples/server/src/examples/server/ServerMain.scala
rename to modules/examples/server/src/main/scala/examples/server/ServerMain.scala
index 7fc5d6e..72c9804 100644
--- a/examples/server/src/examples/server/ServerMain.scala
+++ b/modules/examples/server/src/main/scala/examples/server/ServerMain.scala
@@ -7,7 +7,6 @@ import fs2.io._
 import com.github.plokhotnyuk.jsoniter_scala.core.JsonValueCodec
 import com.github.plokhotnyuk.jsoniter_scala.macros.JsonCodecMaker
 import jsonrpclib.Endpoint
-import cats.syntax.all._
 
 object ServerMain extends IOApp.Simple {
 
diff --git a/fs2/src/jsonrpclib/fs2/CancelTemplate.scala b/modules/fs2/src/main/scala/jsonrpclib/fs2/CancelTemplate.scala
similarity index 100%
rename from fs2/src/jsonrpclib/fs2/CancelTemplate.scala
rename to modules/fs2/src/main/scala/jsonrpclib/fs2/CancelTemplate.scala
diff --git a/fs2/src/jsonrpclib/fs2/FS2Channel.scala b/modules/fs2/src/main/scala/jsonrpclib/fs2/FS2Channel.scala
similarity index 100%
rename from fs2/src/jsonrpclib/fs2/FS2Channel.scala
rename to modules/fs2/src/main/scala/jsonrpclib/fs2/FS2Channel.scala
diff --git a/fs2/src/jsonrpclib/fs2/lsp.scala b/modules/fs2/src/main/scala/jsonrpclib/fs2/lsp.scala
similarity index 99%
rename from fs2/src/jsonrpclib/fs2/lsp.scala
rename to modules/fs2/src/main/scala/jsonrpclib/fs2/lsp.scala
index eeaff1e..29963a7 100644
--- a/fs2/src/jsonrpclib/fs2/lsp.scala
+++ b/modules/fs2/src/main/scala/jsonrpclib/fs2/lsp.scala
@@ -1,7 +1,6 @@
 package jsonrpclib.fs2
 
 import cats.MonadThrow
-import cats.implicits._
 import fs2.Chunk
 import fs2.Stream
 import fs2.Pipe
@@ -14,6 +13,7 @@ import jsonrpclib.Message
 import jsonrpclib.ProtocolError
 import jsonrpclib.Payload.Data
 import jsonrpclib.Payload.NullPayload
+import scala.annotation.tailrec
 
 object lsp {
 
@@ -106,6 +106,7 @@ object lsp {
     case object ReadingBody extends Status
   }
 
+  @tailrec
   private def loop(
       state: ScanState,
       acc: Seq[Chunk[Byte]] = Seq.empty
diff --git a/fs2/src/jsonrpclib/fs2/package.scala b/modules/fs2/src/main/scala/jsonrpclib/fs2/package.scala
similarity index 100%
rename from fs2/src/jsonrpclib/fs2/package.scala
rename to modules/fs2/src/main/scala/jsonrpclib/fs2/package.scala
diff --git a/fs2/test/src/jsonrpclib/fs2/FS2ChannelSpec.scala b/modules/fs2/src/test/scala/jsonrpclib/fs2/FS2ChannelSpec.scala
similarity index 99%
rename from fs2/test/src/jsonrpclib/fs2/FS2ChannelSpec.scala
rename to modules/fs2/src/test/scala/jsonrpclib/fs2/FS2ChannelSpec.scala
index 90f2bae..43b7c60 100644
--- a/fs2/test/src/jsonrpclib/fs2/FS2ChannelSpec.scala
+++ b/modules/fs2/src/test/scala/jsonrpclib/fs2/FS2ChannelSpec.scala
@@ -6,7 +6,6 @@ import com.github.plokhotnyuk.jsoniter_scala.core.JsonValueCodec
 import com.github.plokhotnyuk.jsoniter_scala.macros.JsonCodecMaker
 import fs2.Stream
 import jsonrpclib._
-import jsonrpclib.fs2.FS2Channel
 import weaver._
 
 import scala.concurrent.duration._
diff --git a/project/build.properties b/project/build.properties
new file mode 100644
index 0000000..cc68b53
--- /dev/null
+++ b/project/build.properties
@@ -0,0 +1 @@
+sbt.version=1.10.11
diff --git a/project/plugins.sbt b/project/plugins.sbt
new file mode 100644
index 0000000..6e9bb88
--- /dev/null
+++ b/project/plugins.sbt
@@ -0,0 +1,17 @@
+addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.11")
+
+addSbtPlugin("org.typelevel" % "sbt-tpolecat" % "0.5.2")
+
+addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "1.1.1")
+
+addSbtPlugin("com.eed3si9n" % "sbt-projectmatrix" % "0.10.0")
+
+addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.18.2")
+
+addSbtPlugin("org.scala-native" % "sbt-scala-native" % "0.4.17")
+
+addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "2.3.1")
+
+addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.5.4")
+
+addDependencyTreePlugin