diff --git a/CHANGELOG.md b/CHANGELOG.md
index c8a5a3f..f217169 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## [1.0.0] - 2026-04-21
 
 ### Added
 
@@ -57,6 +57,6 @@ Initial release.
 - Bearer token auth, Gson-based JSON serialization
 - Structured exceptions: `LettrException`, `LettrApiException`, `LettrValidationException`
 
-[Unreleased]: https://github.com/lettr/lettr-java/compare/v0.2.0...HEAD
+[1.0.0]: https://github.com/lettr/lettr-java/compare/v0.2.0...v1.0.0
 [0.2.0]: https://github.com/lettr/lettr-java/compare/v0.1.0...v0.2.0
 [0.1.0]: https://github.com/lettr/lettr-java/releases/tag/v0.1.0
diff --git a/README.md b/README.md
index 0af0ba3..81a60ea 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@ The official Java SDK for the [Lettr](https://lettr.com) Email API. Send transac
 ### Gradle
 
 ```groovy
-implementation 'com.lettr:lettr-java:0.3.0'
+implementation 'com.lettr:lettr-java:1.0.0'
 ```
 
 ### Maven
@@ -16,7 +16,7 @@ implementation 'com.lettr:lettr-java:0.3.0'
 <dependency>
     <groupId>com.lettr</groupId>
     <artifactId>lettr-java</artifactId>
-    <version>0.3.0</version>
+    <version>1.0.0</version>
 </dependency>
 ```
 
diff --git a/gradle.properties b/gradle.properties
index 122306d..0827eec 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,5 +1,5 @@
 GROUP=com.lettr
-VERSION=0.3.0
+VERSION=1.0.0
 POM_ARTIFACT_ID=lettr-java
 POM_NAME=Lettr Java SDK
 POM_DESCRIPTION=Java SDK for the Lettr Email API
diff --git a/src/main/java/com/lettr/core/net/HttpClient.java b/src/main/java/com/lettr/core/net/HttpClient.java
index 46ab5b8..7a69384 100644
--- a/src/main/java/com/lettr/core/net/HttpClient.java
+++ b/src/main/java/com/lettr/core/net/HttpClient.java
@@ -27,7 +27,7 @@
 public class HttpClient {
 
     private static final String BASE_URL = "https://app.lettr.com/api";
-    private static final String USER_AGENT = "lettr-java/0.3.0";
+    private static final String USER_AGENT = "lettr-java/1.0.0";
     private static final Duration DEFAULT_TIMEOUT = Duration.ofSeconds(30);
 
     private final String apiKey;