diff --git a/CHANGELOG.md b/CHANGELOG.md
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..01c24a0c3c7027139f362bd6129e917f5be3fefe 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -0,0 +1,28 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [1.0.0] - 2023-05-06
+
+First stable version of Vigenere-API.
+This update provides an OpenAPI interface to use Caesar algorithm.
+You can cipher and decipher content.
+
+### Added features:
+
+- Caesar algorithm [#1](https://etulab.univ-amu.fr/d19006523/vigenere-api/-/issues/1).
+    - Cipher method at the address: /api/v1/caesar/decipher
+    - Decipher method at the address: /api/v1/caesar/decipher
+  
+    You need to use the POST method to send the JSON content to cipher or decipher.<br>
+    The JSON format is:
+    "content": str
+    "key": int | str(one character)
+- Starter of API.
+    To start the API, install the package and run the command:
+    ```shell
+    python -m vigenere-api
+    ```
diff --git a/pyproject.toml b/pyproject.toml
index 66bb3d790cef09c0aa4b193c24e7bcab6803da85..736c1ae33ca5c130d15f46dfd4c3256d62cab14f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "Vigenere-API"
-version = "0.0.1"
+version = "1.0.0"
 description = """\
 The project provides an API to use cipher, decipher and decrypt method with the Vigenere algorithm.\
 The Caesar algorithm is provided for the cipher method and decipher method.\