diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 2b28d6ec..6d78745c 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "0.8.1"
+  ".": "0.9.0"
 }
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0b36bdd8..1b4d6aac 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,25 @@
 # Changelog
 
+## 0.9.0 (2024-01-08)
+
+Full Changelog: [v0.8.1...v0.9.0](https://github.com/anthropics/anthropic-sdk-python/compare/v0.8.1...v0.9.0)
+
+### Features
+
+* add `None` default value to nullable response properties ([#299](https://github.com/anthropics/anthropic-sdk-python/issues/299)) ([da423db](https://github.com/anthropics/anthropic-sdk-python/commit/da423db5c14b213c52fe0986981c4f01aff0d2c3))
+
+
+### Bug Fixes
+
+* **client:** correctly use custom http client auth ([#296](https://github.com/anthropics/anthropic-sdk-python/issues/296)) ([6289d6e](https://github.com/anthropics/anthropic-sdk-python/commit/6289d6e205f872c02114f05333d5426055f2416f))
+
+
+### Chores
+
+* **internal:** loosen type var restrictions ([#301](https://github.com/anthropics/anthropic-sdk-python/issues/301)) ([5e5e1e7](https://github.com/anthropics/anthropic-sdk-python/commit/5e5e1e716a8732af66e2234307521b4620b07361))
+* **internal:** replace isort with ruff ([#298](https://github.com/anthropics/anthropic-sdk-python/issues/298)) ([7c60904](https://github.com/anthropics/anthropic-sdk-python/commit/7c60904f5da10c4ef6ab8af4e8631bc938b35131))
+* use property declarations for resource members ([#300](https://github.com/anthropics/anthropic-sdk-python/issues/300)) ([8671297](https://github.com/anthropics/anthropic-sdk-python/commit/8671297b87105635accefd574c44dbffd8a4f9e9))
+
 ## 0.8.1 (2023-12-22)
 
 Full Changelog: [v0.8.0...v0.8.1](https://github.com/anthropics/anthropic-sdk-python/compare/v0.8.0...v0.8.1)
diff --git a/pyproject.toml b/pyproject.toml
index d6e3b1b9..8a119ed8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "anthropic"
-version = "0.8.1"
+version = "0.9.0"
 description = "The official Python library for the anthropic API"
 readme = "README.md"
 license = "MIT"
diff --git a/src/anthropic/_version.py b/src/anthropic/_version.py
index 9703c64f..17bb7b81 100644
--- a/src/anthropic/_version.py
+++ b/src/anthropic/_version.py
@@ -1,4 +1,4 @@
 # File generated from our OpenAPI spec by Stainless.
 
 __title__ = "anthropic"
-__version__ = "0.8.1"  # x-release-please-version
+__version__ = "0.9.0"  # x-release-please-version