Resolves the silent strip of Anthropic Structured Outputs across the Vertex AI Claude transformation paths and the Anthropic-adapter re-merge. Consolidates and supersedes four stalled community PRs addressing overlapping aspects of the same root bug: - #23475 (Vertex AI Claude blanket-strip removal) - #23396 (Vertex AI Claude conditional passthrough) - #23706 (Anthropic adapter exclude output_config from non-Anthropic backends) - #22727 (Anthropic adapter strip output_config for non-Anthropic backends) Closes / addresses: #23380 (Vertex AI Claude output_config drop), related: #26423, #25079, #24549, #25971, #25957, #26163, #24856. What was broken --------------- * Vertex AI Claude paths called ``data.pop("output_config")`` and ``data.pop("output_format")`` unconditionally even when Vertex accepted those fields. Callers asking for Structured Outputs got a 200 with prose and never knew the schema constraints had been silently dropped (often masked for months by permissive fallback parsers). * The ``/v1/messages`` -> ``/chat/completions`` adapter (``LiteLLMMessagesToCompletionTransformationHandler``) re-merged the raw Anthropic-shaped ``output_config`` into ``completion_kwargs`` AFTER the translator already mapped its meaningful parts to ``response_format`` / ``reasoning_effort``. Non-Anthropic backends (Azure OpenAI, Fireworks, Bedrock Nova, etc.) then 400'd with "Extra inputs are not permitted". Approach -------- Vertex AI Claude (chat-completion + experimental_pass_through paths): Replace the unconditional pop with a sanitizer ``_sanitize_vertex_anthropic_output_params`` that strips only the Vertex-unsupported keys (today: ``effort``) from ``output_config`` while forwarding ``format`` and the legacy top-level ``output_format``. Defensive: non-dict ``output_config`` values are dropped to avoid sending malformed payloads downstream. Greptile P1 from PR #23396 addressed: when ``output_config`` carries both ``format`` and ``effort``, the prior conditional pass-through forwarded ``effort`` and reproduced the 400. The new helper filters per-key. Anthropic ``/v1/messages`` adapter: Add ``output_config`` to a named module-level constant ``ANTHROPIC_ONLY_REQUEST_KEYS`` and wire it into ``excluded_keys`` so the post-translation re-merge skips re-adding the raw key. This fixes the 400 on non-Anthropic backends and avoids the conflicting duplicate (``response_format`` + raw ``output_config``) on Anthropic-family backends. Greptile P2 from PR #23706 addressed: the constant gives reviewers one grep target instead of an inline literal that silently grows. Greptile P2 from PR #22727 addressed: ``extra_kwargs or {}`` is replaced with explicit ``is None`` checks so empty-dict callers no longer skip the fallback path. Tests ----- * tests/test_litellm/llms/vertex_ai/vertex_ai_partner_models/anthropic/ test_vertex_ai_partner_models_anthropic_transformation.py: - 5 new/updated cases plus a direct unit test for ``_sanitize_vertex_anthropic_output_params``. - Updated ``test_vertex_ai_claude_sonnet_4_5_structured_output_fix`` so its mock-injected ``output_format`` is asserted to FLOW THROUGH (the original test asserted the now-buggy strip behavior). * tests/test_litellm/llms/anthropic/experimental_pass_through/ adapters/test_handler_output_config_passthrough.py (new): - Constant export sanity, output_config strip with ``effort`` only, output_config strip with ``format`` only, regression guard that unrelated extras still flow, explicit-empty-dict path, and the ``extra_kwargs=None`` no-crash path. Test-quality fixes incorporated from Greptile review on the superseded PRs: * No ``inspect.getsource`` source-text assertions (PR #24114 / #23475). * ``sys.path`` insertion is anchored to ``__file__`` (PR #23706). * Assertion messages are positional, not tuple (PR #24114-class bug). * No ``or {}`` masking explicit empty dicts in helper signatures (PR #22727). Verified locally: 26/26 pass with this commit. The new tests fail (or fail to import) on ``main`` without it. Out of scope ------------ * The ``max_tokens`` capping logic from PR #22727 — independent concern, deserves its own PR with a focused test plan. * Architectural rework of the ``excluded_keys`` mechanism (Greptile P2 on PR #23706 noted point-fix growth). The named constant gives maintainers a clear place to extend; a registry-based approach would be a follow-up. Co-Authored-By: netbrah <netbrah> Co-Authored-By: s-zx <s-zx> Co-Authored-By: invoicepulse <invoicepulse> Co-Authored-By: cfdude <cfdude> Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> |
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| litellm | ||
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| CLAUDE.md | ||
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| Makefile | ||
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| model_prices_and_context_window.json | ||
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| provider_endpoints_support.json | ||
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| uv.lock | ||
🚅 LiteLLM
LiteLLM AI Gateway
Open Source AI Gateway for 100+ LLMs. Self-hosted. Enterprise-ready. Call any LLM in OpenAI format.
LiteLLM Proxy Server (AI Gateway) | Hosted Proxy | Enterprise Tier | Website
What is LiteLLM
LiteLLM is an open source AI Gateway that gives you a single, unified interface to call 100+ LLM providers — OpenAI, Anthropic, Gemini, Bedrock, Azure, and more — using the OpenAI format.
Use it as a Python SDK for direct library integration, or deploy the AI Gateway (Proxy Server) as a centralized service for your team or organization.
Jump to LiteLLM Proxy (LLM Gateway) Docs
Jump to Supported LLM Providers
Why LiteLLM
Managing LLM calls across providers gets complicated fast — different SDKs, auth patterns, request formats, and error types for every model. LiteLLM removes that friction:
- Unified API — one interface for 100+ LLMs, no provider-specific SDK juggling
- Drop-in OpenAI compatibility — swap providers without rewriting your code
- Production-ready gateway — virtual keys, spend tracking, guardrails, load balancing, and an admin dashboard out of the box
- 8ms P95 latency at 1k RPS (benchmarks)
OSS Adopters
Netflix |
Features
LLMs - Call 100+ LLMs (Python SDK + AI Gateway)
All Supported Endpoints - /chat/completions, /responses, /embeddings, /images, /audio, /batches, /rerank, /a2a, /messages and more.
Python SDK
uv add litellm
from litellm import completion
import os
os.environ["OPENAI_API_KEY"] = "your-openai-key"
os.environ["ANTHROPIC_API_KEY"] = "your-anthropic-key"
# OpenAI
response = completion(model="openai/gpt-4o", messages=[{"role": "user", "content": "Hello!"}])
# Anthropic
response = completion(model="anthropic/claude-sonnet-4-20250514", messages=[{"role": "user", "content": "Hello!"}])
AI Gateway (Proxy Server)
Getting Started - E2E Tutorial - Setup virtual keys, make your first request
uv tool install 'litellm[proxy]'
litellm --model gpt-4o
import openai
client = openai.OpenAI(api_key="anything", base_url="http://0.0.0.0:4000")
response = client.chat.completions.create(
model="gpt-4o",
messages=[{"role": "user", "content": "Hello!"}]
)
Agents - Invoke A2A Agents (Python SDK + AI Gateway)
Supported Providers - LangGraph, Vertex AI Agent Engine, Azure AI Foundry, Bedrock AgentCore, Pydantic AI
Python SDK - A2A Protocol
from litellm.a2a_protocol import A2AClient
from a2a.types import SendMessageRequest, MessageSendParams
from uuid import uuid4
client = A2AClient(base_url="http://localhost:10001")
request = SendMessageRequest(
id=str(uuid4()),
params=MessageSendParams(
message={
"role": "user",
"parts": [{"kind": "text", "text": "Hello!"}],
"messageId": uuid4().hex,
}
)
)
response = await client.send_message(request)
AI Gateway (Proxy Server)
Step 1. Add your Agent to the AI Gateway
Step 2. Call Agent via A2A SDK
from a2a.client import A2ACardResolver, A2AClient
from a2a.types import MessageSendParams, SendMessageRequest
from uuid import uuid4
import httpx
base_url = "http://localhost:4000/a2a/my-agent" # LiteLLM proxy + agent name
headers = {"Authorization": "Bearer sk-1234"} # LiteLLM Virtual Key
async with httpx.AsyncClient(headers=headers) as httpx_client:
resolver = A2ACardResolver(httpx_client=httpx_client, base_url=base_url)
agent_card = await resolver.get_agent_card()
client = A2AClient(httpx_client=httpx_client, agent_card=agent_card)
request = SendMessageRequest(
id=str(uuid4()),
params=MessageSendParams(
message={
"role": "user",
"parts": [{"kind": "text", "text": "Hello!"}],
"messageId": uuid4().hex,
}
)
)
response = await client.send_message(request)
MCP Tools - Connect MCP servers to any LLM (Python SDK + AI Gateway)
Python SDK - MCP Bridge
from mcp import ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client
from litellm import experimental_mcp_client
import litellm
server_params = StdioServerParameters(command="python", args=["mcp_server.py"])
async with stdio_client(server_params) as (read, write):
async with ClientSession(read, write) as session:
await session.initialize()
# Load MCP tools in OpenAI format
tools = await experimental_mcp_client.load_mcp_tools(session=session, format="openai")
# Use with any LiteLLM model
response = await litellm.acompletion(
model="gpt-4o",
messages=[{"role": "user", "content": "What's 3 + 5?"}],
tools=tools
)
AI Gateway - MCP Gateway
Step 1. Add your MCP Server to the AI Gateway
Step 2. Call MCP tools via /chat/completions
curl -X POST 'http://0.0.0.0:4000/v1/chat/completions' \
-H 'Authorization: Bearer sk-1234' \
-H 'Content-Type: application/json' \
-d '{
"model": "gpt-4o",
"messages": [{"role": "user", "content": "Summarize the latest open PR"}],
"tools": [{
"type": "mcp",
"server_url": "litellm_proxy/mcp/github",
"server_label": "github_mcp",
"require_approval": "never"
}]
}'
Use with Cursor IDE
{
"mcpServers": {
"LiteLLM": {
"url": "http://localhost:4000/mcp/",
"headers": {
"x-litellm-api-key": "Bearer sk-1234"
}
}
}
}
Supported Providers (Website Supported Models | Docs)
Get Started
You can use LiteLLM through either the Proxy Server or Python SDK. Both give you a unified interface to access multiple LLMs (100+ LLMs). Choose the option that best fits your needs:
| LiteLLM AI Gateway | LiteLLM Python SDK | |
|---|---|---|
| Use Case | Central service (LLM Gateway) to access multiple LLMs | Use LiteLLM directly in your Python code |
| Who Uses It? | Gen AI Enablement / ML Platform Teams | Developers building LLM projects |
| Key Features | Centralized API gateway with authentication and authorization, multi-tenant cost tracking and spend management per project/user, per-project customization (logging, guardrails, caching), virtual keys for secure access control, admin dashboard UI for monitoring and management | Direct Python library integration in your codebase, Router with retry/fallback logic across multiple deployments (e.g. Azure/OpenAI) - Router, application-level load balancing and cost tracking, exception handling with OpenAI-compatible errors, observability callbacks (Lunary, MLflow, Langfuse, etc.) |
Stable Release: Use docker images with the -stable tag. These have undergone 12 hour load tests, before being published. More information about the release cycle here
Support for more providers. Missing a provider or LLM Platform, raise a feature request.
Run in Developer Mode
Services
- Setup .env file in root
- Run dependant services
docker-compose up db prometheus
Backend
- (In root) create virtual environment
python -m venv .venv - Activate virtual environment
source .venv/bin/activate - Install dependencies
uv sync --all-extras --group proxy-dev uv run prisma generateprisma generate- Start proxy backend
python litellm/proxy/proxy_cli.py
Frontend
- Navigate to
ui/litellm-dashboard - Install dependencies
npm install - Run
npm run devto start the dashboard
Verify Docker Image Signatures
All LiteLLM Docker images published to GHCR are signed with cosign. Every release is signed with the same key introduced in commit 0112e53.
Verify using the pinned commit hash (recommended):
A commit hash is cryptographically immutable, so this is the strongest way to ensure you are using the original signing key:
cosign verify \
--key https://raw.githubusercontent.com/BerriAI/litellm/0112e53046018d726492c814b3644b7d376029d0/cosign.pub \
ghcr.io/berriai/litellm:<release-tag>
Verify using a release tag (convenience):
Tags are protected in this repository and resolve to the same key. This option is easier to read but relies on tag protection rules:
cosign verify \
--key https://raw.githubusercontent.com/BerriAI/litellm/<release-tag>/cosign.pub \
ghcr.io/berriai/litellm:<release-tag>
Replace <release-tag> with the version you are deploying (e.g. v1.83.0-stable).
Enterprise
For companies that need better security, user management and professional support
Get an Enterprise License Talk to founders
This covers:
- ✅ Features under the LiteLLM Commercial License:
- ✅ Feature Prioritization
- ✅ Custom Integrations
- ✅ Professional Support - Dedicated discord + slack
- ✅ Custom SLAs
- ✅ Secure access with Single Sign-On
Contributing
We welcome contributions to LiteLLM! Whether you're fixing bugs, adding features, or improving documentation, we appreciate your help.
Quick Start for Contributors
This requires uv to be installed.
git clone https://github.com/BerriAI/litellm.git
cd litellm
make install-dev # Install development dependencies
make format # Format your code
make lint # Run all linting checks
make test-unit # Run unit tests
make format-check # Check formatting only
For detailed contributing guidelines, see CONTRIBUTING.md.
Code Quality / Linting
LiteLLM follows the Google Python Style Guide.
Our automated checks include:
- Black for code formatting
- Ruff for linting and code quality
- MyPy for type checking
- Circular import detection
- Import safety checks
All these checks must pass before your PR can be merged.
Support / talk with founders
- Schedule Demo 👋
- Community Discord 💭
- Community Slack 💭
- Our emails ✉️ ishaan@berri.ai / krrish@berri.ai