diff --git a/frameworks/Kotlin/vertx-web-kotlinx/.gitignore b/frameworks/Kotlin/vertx-web-kotlinx/.gitignore
new file mode 100644
index 000000000000..eb713db19674
--- /dev/null
+++ b/frameworks/Kotlin/vertx-web-kotlinx/.gitignore
@@ -0,0 +1 @@
+.m2
diff --git a/frameworks/Kotlin/vertx-web-kotlinx/build.gradle.kts b/frameworks/Kotlin/vertx-web-kotlinx/build.gradle.kts
index 2e0035ab3e76..a9eb1c72af03 100644
--- a/frameworks/Kotlin/vertx-web-kotlinx/build.gradle.kts
+++ b/frameworks/Kotlin/vertx-web-kotlinx/build.gradle.kts
@@ -10,11 +10,12 @@ plugins {
 }
 
 repositories {
+    mavenLocal() // TODO
     mavenCentral()
 }
 
 val vertxVersion = "4.5.10"
-val kotlinxSerializationVersion = "1.7.3"
+val kotlinxSerializationVersion = "1.7.4-vertx-buffer-SNAPSHOT" // TODO
 dependencies {
     implementation(platform("io.vertx:vertx-stack-depchain:$vertxVersion"))
     implementation("io.vertx:vertx-web")
@@ -30,6 +31,7 @@ dependencies {
 
     implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:$kotlinxSerializationVersion")
     implementation("org.jetbrains.kotlinx:kotlinx-serialization-json-io:$kotlinxSerializationVersion")
+    implementation("org.jetbrains.kotlinx:kotlinx-serialization-json-vertx:$kotlinxSerializationVersion")
     implementation("org.jetbrains.kotlinx:kotlinx-io-core:0.5.4")
 
     implementation("org.jetbrains.kotlinx:kotlinx-html:0.11.0")
diff --git a/frameworks/Kotlin/vertx-web-kotlinx/copy_maven_local.sh b/frameworks/Kotlin/vertx-web-kotlinx/copy_maven_local.sh
new file mode 100755
index 000000000000..e3e3282e0878
--- /dev/null
+++ b/frameworks/Kotlin/vertx-web-kotlinx/copy_maven_local.sh
@@ -0,0 +1,2 @@
+mkdir -p .m2/repository/org/jetbrains/kotlinx/
+cp -r ~/.m2/repository/org/jetbrains/kotlinx/kotlinx-serialization-* .m2/repository/org/jetbrains/kotlinx/
diff --git a/frameworks/Kotlin/vertx-web-kotlinx/src/main/kotlin/KotlinxIo.kt b/frameworks/Kotlin/vertx-web-kotlinx/src/main/kotlin/KotlinxIo.kt
deleted file mode 100644
index 6427b91e85ef..000000000000
--- a/frameworks/Kotlin/vertx-web-kotlinx/src/main/kotlin/KotlinxIo.kt
+++ /dev/null
@@ -1,47 +0,0 @@
-import io.vertx.core.streams.WriteStream
-import io.vertx.kotlin.coroutines.coAwait
-import kotlinx.coroutines.runBlocking
-import kotlinx.io.RawSink
-import kotlinx.io.readByteArray
-import io.vertx.core.buffer.Buffer as VertxBuffer
-import kotlinx.io.Buffer as KotlinxIoBuffer
-
-@Suppress("NOTHING_TO_INLINE")
-private inline fun Long.toIntOrThrow(): Int {
-    require(this in Int.MIN_VALUE.toLong()..Int.MAX_VALUE.toLong())
-    return toInt()
-}
-
-@JvmInline
-value class VertxBufferWriteStreamRawSink(val writeStream: WriteStream<VertxBuffer>) : RawSink {
-    override fun write(source: KotlinxIoBuffer, byteCount: Long) {
-        runBlocking {
-            writeStream.write(VertxBuffer.buffer(source.readByteArray(byteCount.toIntOrThrow()))).coAwait()
-        }
-    }
-
-    override fun flush() {}
-
-    override fun close() {
-        writeStream.end()
-    }
-}
-
-// not used currently
-fun WriteStream<VertxBuffer>.toRawSink(): RawSink =
-    VertxBufferWriteStreamRawSink(this)
-
-
-@JvmInline
-value class VertxBufferRawSink(val vertxBuffer: VertxBuffer) : RawSink {
-    override fun write(source: KotlinxIoBuffer, byteCount: Long) {
-        vertxBuffer.appendBytes(source.readByteArray(byteCount.toIntOrThrow()))
-    }
-
-    override fun flush() {}
-
-    override fun close() {}
-}
-
-fun VertxBuffer.toRawSink(): RawSink =
-    VertxBufferRawSink(this)
diff --git a/frameworks/Kotlin/vertx-web-kotlinx/src/main/kotlin/MainVerticle.kt b/frameworks/Kotlin/vertx-web-kotlinx/src/main/kotlin/MainVerticle.kt
index 2bd701fa0838..77d5bee2e61e 100644
--- a/frameworks/Kotlin/vertx-web-kotlinx/src/main/kotlin/MainVerticle.kt
+++ b/frameworks/Kotlin/vertx-web-kotlinx/src/main/kotlin/MainVerticle.kt
@@ -20,12 +20,11 @@ import io.vertx.sqlclient.Tuple
 import kotlinx.coroutines.Dispatchers
 import kotlinx.html.*
 import kotlinx.html.stream.appendHTML
-import kotlinx.io.buffered
 import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.SerializationStrategy
 import kotlinx.serialization.json.Json
-import kotlinx.serialization.json.io.encodeToSink
+import kotlinx.serialization.json.vertx.encodeToBuffer
 import java.time.ZonedDateTime
 import java.time.format.DateTimeFormatter
 
@@ -134,11 +133,9 @@ class MainVerticle(val hasDb: Boolean) : CoroutineVerticle(), CoroutineRouterSup
                 */
 
                 // approach 3
-                end(Buffer.buffer().apply {
-                    toRawSink().buffered().use { bufferedSink ->
-                        @OptIn(ExperimentalSerializationApi::class)
-                        Json.encodeToSink(serializer, requestHandler(it), bufferedSink)
-                    }
+                end(Buffer.buffer().also { buffer ->
+                    @OptIn(ExperimentalSerializationApi::class)
+                    Json.encodeToBuffer(serializer, requestHandler(it), buffer)
                 })
             }
         }
diff --git a/frameworks/Kotlin/vertx-web-kotlinx/vertx-web-kotlinx-postgresql.dockerfile b/frameworks/Kotlin/vertx-web-kotlinx/vertx-web-kotlinx-postgresql.dockerfile
index 17b43ebcb5c3..1e704fc27d01 100644
--- a/frameworks/Kotlin/vertx-web-kotlinx/vertx-web-kotlinx-postgresql.dockerfile
+++ b/frameworks/Kotlin/vertx-web-kotlinx/vertx-web-kotlinx-postgresql.dockerfile
@@ -1,5 +1,7 @@
 FROM gradle:8.10.2-jdk21
 
+# Publish the dependencies to Maven local and run "copy_maven_local.sh" first.
+COPY .m2/repository/org/jetbrains/kotlinx /root/.m2/repository/org/jetbrains/kotlinx
 WORKDIR /vertx-web-kotlinx
 COPY build.gradle.kts build.gradle.kts
 COPY settings.gradle.kts settings.gradle.kts
diff --git a/frameworks/Kotlin/vertx-web-kotlinx/vertx-web-kotlinx.dockerfile b/frameworks/Kotlin/vertx-web-kotlinx/vertx-web-kotlinx.dockerfile
index 4bdc993707dc..07fff6b9a576 100644
--- a/frameworks/Kotlin/vertx-web-kotlinx/vertx-web-kotlinx.dockerfile
+++ b/frameworks/Kotlin/vertx-web-kotlinx/vertx-web-kotlinx.dockerfile
@@ -1,5 +1,7 @@
 FROM gradle:8.10.2-jdk21
 
+# Publish the dependencies to Maven local and run "copy_maven_local.sh" first.
+COPY .m2/repository/org/jetbrains/kotlinx /root/.m2/repository/org/jetbrains/kotlinx
 WORKDIR /vertx-web-kotlinx
 COPY build.gradle.kts build.gradle.kts
 COPY settings.gradle.kts settings.gradle.kts