diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4903e33..348d023 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,23 @@
 
 All notable changes to this project will be documented in this file.
 
+## [0.4.0] - 2026-05-08
+
+### Features
+
+- [**breaking**] Add Codec abstraction with JSON, MessagePack, and Raw codecs([efc1d5a](https://github.com/zheylmun/socketeer/commit/efc1d5a22e12a40d2584626f49e42930e9725902))
+
+### Bug Fixes
+
+- Mark Error::Codec inner as #[source]([ffdca32](https://github.com/zheylmun/socketeer/commit/ffdca32e38aed73c8b656590264da4337f83d848))
+- Surface peer close as WebsocketClosed in HandshakeContext::recv([cd67288](https://github.com/zheylmun/socketeer/commit/cd6728804ae8229a0f7a62172c460022c59acb35))
+
+### Testing
+
+- Add coverage for Codec trait and new HandshakeContext paths([aeb3c89](https://github.com/zheylmun/socketeer/commit/aeb3c8964ae9a8d21fc67a4b31fb4a9700c7c525))
+- Push coverage to 98% lines / 96% regions([09d7364](https://github.com/zheylmun/socketeer/commit/09d7364f9e0ee018c5d111335c912544a96eabed))
+- Clarify raw-API test names and cover send_raw directly([b10d987](https://github.com/zheylmun/socketeer/commit/b10d98707a3a140daba6dc0fd8d0d41a3cd64ef7))
+
 ## [0.3.0] - 2026-04-10
 
 ### Features
diff --git a/Cargo.lock b/Cargo.lock
index 9139edf..12594eb 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -863,7 +863,7 @@ dependencies = [
 
 [[package]]
 name = "socketeer"
-version = "0.3.0"
+version = "0.4.0"
 dependencies = [
  "bytes",
  "futures",
diff --git a/Cargo.toml b/Cargo.toml
index aec5284..a37960f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "socketeer"
-version = "0.3.0"
+version = "0.4.0"
 edition = "2024"
 rust-version = "1.85"
 description = "Simplified websocket client based on Tokio-Tungstenite"