diff --git a/docs/my-website/docs/proxy/config_settings.md b/docs/my-website/docs/proxy/config_settings.md
index f76fd214682..67fffc13e4b 100644
--- a/docs/my-website/docs/proxy/config_settings.md
+++ b/docs/my-website/docs/proxy/config_settings.md
@@ -397,6 +397,7 @@ router_settings:
 | AUDIO_SPEECH_CHUNK_SIZE | Chunk size for audio speech processing. Default is 1024
 | ANTHROPIC_API_KEY | API key for Anthropic service
 | ANTHROPIC_API_BASE | Base URL for Anthropic API. Default is https://api.anthropic.com
+| ANTHROPIC_TOKEN_COUNTING_BETA_VERSION | Beta version header for Anthropic token counting API. Default is `token-counting-2024-11-01`
 | AWS_ACCESS_KEY_ID | Access Key ID for AWS services
 | AWS_BATCH_ROLE_ARN | ARN of the AWS IAM role for batch operations
 | AWS_DEFAULT_REGION | Default AWS region for service interactions when AWS_REGION is not set
@@ -412,6 +413,8 @@ router_settings:
 | AWS_WEB_IDENTITY_TOKEN | Web identity token for AWS
 | AWS_WEB_IDENTITY_TOKEN_FILE | Path to file containing web identity token for AWS
 | AZURE_API_VERSION | Version of the Azure API being used
+| AZURE_AI_API_BASE | Base URL for Azure AI services (e.g., Azure AI Anthropic)
+| AZURE_AI_API_KEY | API key for Azure AI services (e.g., Azure AI Anthropic)
 | AZURE_AUTHORITY_HOST | Azure authority host URL
 | AZURE_CERTIFICATE_PASSWORD | Password for Azure OpenAI certificate
 | AZURE_CLIENT_ID | Client ID for Azure services
diff --git a/litellm/llms/anthropic/common_utils.py b/litellm/llms/anthropic/common_utils.py
index ccfbc36c080..437a972f4df 100644
--- a/litellm/llms/anthropic/common_utils.py
+++ b/litellm/llms/anthropic/common_utils.py
@@ -14,6 +14,8 @@ from litellm.llms.base_llm.base_utils import BaseLLMModelInfo, BaseTokenCounter
 from litellm.llms.base_llm.chat.transformation import BaseLLMException
 from litellm.types.llms.anthropic import (
     ANTHROPIC_HOSTED_TOOLS,
+    ANTHROPIC_OAUTH_BETA_HEADER,
+    ANTHROPIC_OAUTH_TOKEN_PREFIX,
     AllAnthropicToolsValues,
     AnthropicMcpServerTool,
 )
@@ -371,6 +373,8 @@ class AnthropicModelInfo(BaseLLMModelInfo):
         api_key: Optional[str] = None,
         api_base: Optional[str] = None,
     ) -> Dict:
+        # Check for Anthropic OAuth token in headers
+        headers, api_key = optionally_handle_anthropic_oauth(headers=headers, api_key=api_key)
         if api_key is None:
             raise litellm.AuthenticationError(
                 message="Missing Anthropic API Key - A call is being made to anthropic but no key is set either in the environment variables or via params. Please set `ANTHROPIC_API_KEY` in your environment vars",
diff --git a/litellm/llms/anthropic/experimental_pass_through/messages/transformation.py b/litellm/llms/anthropic/experimental_pass_through/messages/transformation.py
index f67e4c8382c..7135102db01 100644
--- a/litellm/llms/anthropic/experimental_pass_through/messages/transformation.py
+++ b/litellm/llms/anthropic/experimental_pass_through/messages/transformation.py
@@ -17,7 +17,11 @@ from litellm.types.llms.anthropic_messages.anthropic_response import (
 from litellm.types.llms.anthropic_tool_search import get_tool_search_beta_header
 from litellm.types.router import GenericLiteLLMParams
 
-from ...common_utils import AnthropicError, AnthropicModelInfo
+from ...common_utils import (
+    AnthropicError,
+    AnthropicModelInfo,
+    optionally_handle_anthropic_oauth,
+)
 
 DEFAULT_ANTHROPIC_API_BASE = "https://api.anthropic.com"
 DEFAULT_ANTHROPIC_API_VERSION = "2023-06-01"
@@ -68,8 +72,11 @@ class AnthropicMessagesConfig(BaseAnthropicMessagesConfig):
     ) -> Tuple[dict, Optional[str]]:
         import os
 
+        # Check for Anthropic OAuth token in Authorization header
+        headers, api_key = optionally_handle_anthropic_oauth(headers=headers, api_key=api_key)
         if api_key is None:
             api_key = os.getenv("ANTHROPIC_API_KEY")
+
         if "x-api-key" not in headers and api_key:
             headers["x-api-key"] = api_key
         if "anthropic-version" not in headers:
diff --git a/litellm/types/llms/anthropic.py b/litellm/types/llms/anthropic.py
index 779a6950d92..0e687be660f 100644
--- a/litellm/types/llms/anthropic.py
+++ b/litellm/types/llms/anthropic.py
@@ -642,4 +642,8 @@ ANTHROPIC_TOOL_SEARCH_BETA_HEADER = "advanced-tool-use-2025-11-20"
 # Effort beta header constant
 ANTHROPIC_EFFORT_BETA_HEADER = "effort-2025-11-24"
 
+# OAuth constants
+ANTHROPIC_OAUTH_TOKEN_PREFIX = "sk-ant-oat"
+ANTHROPIC_OAUTH_BETA_HEADER = "oauth-2025-04-20"
+
 
diff --git a/tests/test_litellm/llms/anthropic/test_anthropic_common_utils.py b/tests/test_litellm/llms/anthropic/test_anthropic_common_utils.py
new file mode 100644
index 00000000000..0a397d116e7
--- /dev/null
+++ b/tests/test_litellm/llms/anthropic/test_anthropic_common_utils.py
@@ -0,0 +1,84 @@
+"""
+Tests for Anthropic OAuth token handling for Claude Code Max integration.
+"""
+
+import os
+import sys
+
+# Add litellm to path
+sys.path.insert(0, os.path.abspath("../../../../.."))
+
+# Fake OAuth token for testing (not a real secret)
+FAKE_OAUTH_TOKEN = "sk-ant-oat01-fake-token-for-testing-123456789abcdef"
+
+
+def test_oauth_detection_in_common_utils():
+    """Test 1: OAuth token detection in common_utils"""
+    from litellm.llms.anthropic.common_utils import optionally_handle_anthropic_oauth
+
+    headers = {"authorization": f"Bearer {FAKE_OAUTH_TOKEN}"}
+    updated_headers, extracted_api_key = optionally_handle_anthropic_oauth(headers, None)
+
+    assert extracted_api_key == FAKE_OAUTH_TOKEN
+    assert updated_headers["anthropic-beta"] == "oauth-2025-04-20"
+    assert updated_headers["anthropic-dangerous-direct-browser-access"] == "true"
+
+
+def test_oauth_integration_in_validate_environment():
+    """Test 2: OAuth integration in AnthropicConfig validate_environment"""
+    from litellm.llms.anthropic.common_utils import AnthropicModelInfo
+
+    config = AnthropicModelInfo()
+    headers = {"authorization": f"Bearer {FAKE_OAUTH_TOKEN}"}
+
+    updated_headers = config.validate_environment(
+        headers=headers,
+        model="claude-3-haiku-20240307",
+        messages=[{"role": "user", "content": "Hello"}],
+        optional_params={},
+        litellm_params={},
+        api_key=None,
+        api_base=None,
+    )
+
+    assert updated_headers["x-api-key"] == FAKE_OAUTH_TOKEN
+    assert updated_headers["anthropic-dangerous-direct-browser-access"] == "true"
+
+
+def test_oauth_detection_in_messages_transformation():
+    """Test 3: OAuth detection in messages transformation"""
+    from litellm.llms.anthropic.experimental_pass_through.messages.transformation import (
+        AnthropicMessagesConfig,
+    )
+
+    config = AnthropicMessagesConfig()
+    headers = {"authorization": f"Bearer {FAKE_OAUTH_TOKEN}"}
+
+    updated_headers, _ = config.validate_anthropic_messages_environment(
+        headers=headers,
+        model="claude-3-haiku-20240307",
+        messages=[{"role": "user", "content": "Hello"}],
+        optional_params={},
+        litellm_params={},
+        api_key=None,
+        api_base=None,
+    )
+
+    assert updated_headers["x-api-key"] == FAKE_OAUTH_TOKEN
+    assert "oauth-2025-04-20" in updated_headers["anthropic-beta"]
+    assert updated_headers["anthropic-dangerous-direct-browser-access"] == "true"
+
+
+def test_regular_api_keys_still_work():
+    """Test 4: Regular API keys still work (regression test)"""
+    from litellm.llms.anthropic.common_utils import optionally_handle_anthropic_oauth
+
+    regular_key = "sk-ant-api03-regular-key-123"
+    headers = {"authorization": f"Bearer {regular_key}"}
+
+    updated_headers, extracted_api_key = optionally_handle_anthropic_oauth(headers, regular_key)
+
+    # Regular key should be unchanged
+    assert extracted_api_key == regular_key
+    # OAuth headers should NOT be added
+    assert "anthropic-dangerous-direct-browser-access" not in updated_headers
\ No newline at end of file
diff --git a/tests/unified_google_tests/test_vertex_ai_native.py b/tests/unified_google_tests/test_vertex_ai_native.py
index 5c8f8575c42..c2f378523ef 100644
--- a/tests/unified_google_tests/test_vertex_ai_native.py
+++ b/tests/unified_google_tests/test_vertex_ai_native.py
@@ -6,5 +6,5 @@ class TestVertexAIGenerateContent(BaseGoogleGenAITest):
     @property
     def model_config(self):
         return {
-            "model": "vertex_ai/gemini-2.5-flash-lite",
+            "model": "vertex_ai/gemini-3-flash-preview",
         }
\ No newline at end of file