diff --git a/.scalafix.conf b/.scalafix.conf
new file mode 100644
index 0000000000..868d5d363a
--- /dev/null
+++ b/.scalafix.conf
@@ -0,0 +1,12 @@
+rules = [
+  # ExplicitResultTypes,
+  # OrganizeImports,
+  # RemoveUnused,
+  DisableSyntax,
+  LeakingImplicitClassVal,
+  NoValInForComprehension,
+  # ProcedureSyntax, // Scala-2 only
+  // Need to preserve string-interpolation prefix for `s"..."` and `f"..."` for
+  // preservinng the code alignment
+  # RedundantSyntax
+]
diff --git a/airframe-di/src/main/scala/wvlet/airframe/Session.scala b/airframe-di/src/main/scala/wvlet/airframe/Session.scala
index a4e3ab2fdb..e19b561b94 100644
--- a/airframe-di/src/main/scala/wvlet/airframe/Session.scala
+++ b/airframe-di/src/main/scala/wvlet/airframe/Session.scala
@@ -136,7 +136,7 @@ object Session extends LogSupport {
     *
     * @param session
     */
-  implicit class SessionAccess(val session: Session) extends AnyVal {
+  implicit class SessionAccess(private val session: Session) extends AnyVal {
     def get[A](surface: Surface)(implicit sourceCode: SourceCode): A = session.get[A](surface)(sourceCode)
     def getOrElse[A](surface: Surface, obj: => A)(implicit sourceCode: SourceCode): A =
       session.getOrElse[A](surface, obj)(sourceCode)
diff --git a/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/client/HttpClientGenerator.scala b/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/client/HttpClientGenerator.scala
index b7b109c700..1f8d5b1840 100644
--- a/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/client/HttpClientGenerator.scala
+++ b/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/client/HttpClientGenerator.scala
@@ -43,7 +43,7 @@ object HttpClientGenerator extends LogSupport {
     }
   }
 
-  private[client] implicit class RichSurface(val s: Surface) extends AnyVal {
+  private[client] implicit class RichSurface(private val s: Surface) extends AnyVal {
     def fullTypeName: String = fullTypeNameOf(s)
   }
 
diff --git a/airframe-http-grpc/src/main/scala/wvlet/airframe/http/grpc/GrpcContext.scala b/airframe-http-grpc/src/main/scala/wvlet/airframe/http/grpc/GrpcContext.scala
index 4668abe9f5..c145b1e36b 100644
--- a/airframe-http-grpc/src/main/scala/wvlet/airframe/http/grpc/GrpcContext.scala
+++ b/airframe-http-grpc/src/main/scala/wvlet/airframe/http/grpc/GrpcContext.scala
@@ -35,7 +35,7 @@ object GrpcContext {
   private[grpc] val KEY_ACCEPT       = Metadata.Key.of("accept", Metadata.ASCII_STRING_MARSHALLER)
   private[grpc] val KEY_CONTENT_TYPE = Metadata.Key.of("content-type", Metadata.ASCII_STRING_MARSHALLER)
 
-  private[grpc] implicit class RichMetadata(val m: Metadata) extends AnyVal {
+  private[grpc] implicit class RichMetadata(private val m: Metadata) extends AnyVal {
     def accept: String = Option(m.get(KEY_ACCEPT)).getOrElse(RPCEncoding.ApplicationMsgPack)
     def setAccept(s: String): Unit = {
       m.removeAll(KEY_ACCEPT)
diff --git a/airframe-http-grpc/src/main/scala/wvlet/airframe/http/grpc/internal/GrpcServiceBuilder.scala b/airframe-http-grpc/src/main/scala/wvlet/airframe/http/grpc/internal/GrpcServiceBuilder.scala
index ca15d180ee..5a1830c0f4 100644
--- a/airframe-http-grpc/src/main/scala/wvlet/airframe/http/grpc/internal/GrpcServiceBuilder.scala
+++ b/airframe-http-grpc/src/main/scala/wvlet/airframe/http/grpc/internal/GrpcServiceBuilder.scala
@@ -36,7 +36,7 @@ import java.util.concurrent.ExecutorService
 /**
   */
 object GrpcServiceBuilder {
-  private implicit class RichMethod(val m: MethodSurface) extends AnyVal {
+  private implicit class RichMethod(private val m: MethodSurface) extends AnyVal {
 
     private def findClientStreamingArg: Option[MethodParameter] = {
       m.args.find(x => classOf[Rx[_]].isAssignableFrom(x.surface.rawType))
diff --git a/airframe-json/src/main/scala/wvlet/airframe/json/package.scala b/airframe-json/src/main/scala/wvlet/airframe/json/package.scala
index 0589cf3926..005ddc834d 100644
--- a/airframe-json/src/main/scala/wvlet/airframe/json/package.scala
+++ b/airframe-json/src/main/scala/wvlet/airframe/json/package.scala
@@ -29,11 +29,11 @@ package object json {
   // Alias to encode msgpack into JSON strings with airframe-codec
   type Json = String
 
-  implicit class RichJson(val json: Json) extends AnyVal {
+  implicit class RichJson(private val json: Json) extends AnyVal {
     def toJSONValue: JSONValue = JSON.parseAny(json)
   }
 
-  implicit class JSONValueOps(val jsonValue: JSONValue) extends AnyVal {
+  implicit class JSONValueOps(private val jsonValue: JSONValue) extends AnyVal {
     def /(name: String): Seq[JSONValue] = {
       jsonValue match {
         case jsonObject: JSONObject =>
@@ -95,7 +95,7 @@ package object json {
     }
   }
 
-  implicit class JSONValueSeqOps(val jsonValues: Seq[JSONValue]) extends AnyVal {
+  implicit class JSONValueSeqOps(private val jsonValues: Seq[JSONValue]) extends AnyVal {
     def /(name: String): Seq[JSONValue] = {
       jsonValues.flatMap { jsonValue => jsonValue / name }
     }
diff --git a/airframe-rx/src/main/scala/wvlet/airframe/rx/package.scala b/airframe-rx/src/main/scala/wvlet/airframe/rx/package.scala
index e3dd0bc390..b8545e412f 100644
--- a/airframe-rx/src/main/scala/wvlet/airframe/rx/package.scala
+++ b/airframe-rx/src/main/scala/wvlet/airframe/rx/package.scala
@@ -17,7 +17,7 @@ import scala.concurrent.{ExecutionContext, Future}
 /**
   */
 package object rx {
-  implicit class FutureConverter[A](val f: Future[A]) extends AnyVal {
+  implicit class FutureConverter[A](private val f: Future[A]) extends AnyVal {
     def toRx(implicit ec: ExecutionContext): RxOption[A] = Rx.fromFuture(f)(ec)
   }
 }
diff --git a/project/plugin.sbt b/project/plugin.sbt
index 2c812601d1..71fd69ee66 100755
--- a/project/plugin.sbt
+++ b/project/plugin.sbt
@@ -10,6 +10,9 @@ addSbtPlugin("org.portable-scala"  % "sbt-scalajs-crossproject" % "1.3.2")
 addSbtPlugin("com.eed3si9n"        % "sbt-buildinfo"            % "0.11.0")
 addSbtPlugin("org.jetbrains.scala" % "sbt-ide-settings"         % "1.1.2")
 
+// For auto-code rewrite
+addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.11.1")
+
 // For integration testing
 val SBT_AIRFRAME_VERSION = sys.env.getOrElse("SBT_AIRFRAME_VERSION", "23.11.3")
 addSbtPlugin("org.wvlet.airframe" % "sbt-airframe" % SBT_AIRFRAME_VERSION)