* feat(mcp): thread the caller token into tools/list discovery for token_exchange
A token_exchange (OBO) server's tools could not be discovered through the aggregator: the list path
never threaded the caller's token, so every tools/list hit the no-subject branch. v1 masked this with
its client_credentials fallback (discovery used a service token); v2 dropped that fallback, so listing
had no credential and the OBO server's tools never appeared - and an MCP client lists before it calls.
Thread the inbound subject_token into the list path the same way the call path does, gated on
auth_type oauth2_token_exchange so the caller's bearer never leaks into other modes:
_get_tools_from_server takes an oauth2_headers param, extracts the token via _extract_bearer_token, and
passes it to _create_mcp_client; server.py forwards oauth2_headers at the list call site.
authorization_code (resolves off identity plus stored token), the static/config modes, and the
background registry refresh are unaffected, and the list path's existing graceful degradation
(catch -> empty list) is preserved.
* fix(mcp): harden token_exchange OBO from the audit (strip, TTL/expires_in, subject_token_type)
- _should_strip_caller_authorization returns True for oauth2_token_exchange, so the inbound subject
token is never forwarded upstream raw - only the IdP-exchanged token is (matches authorization_code).
- _parse_expires_in accepts a JSON float / numeric-string expires_in, and _ttl_seconds caps the cache
TTL at the token's real remaining lifetime so a short-lived exchanged token is never served stale.
- to_server_spec normalizes a falsy subject_token_type to the default URN, parity with v1.
The subject/key disambiguation (never exchange the LiteLLM key; Authorization: Bearer <litellm-key>
support for /mcp) is intentionally a separate cross-cutting PR off staging, not part of this OBO work.
* fix(mcp): stop caller header bypassing OBO exchange; thread subject into prompts/resources
The per-server x-mcp-* override guard in _create_mcp_client only kept the v2 spec
for authorization_code, so a caller-supplied header silently disabled the RFC 8693
exchange on a token_exchange server and forwarded the raw bearer upstream. Extend
the guard to token_exchange so the exchange always runs and the caller cannot
substitute an arbitrary upstream credential.
prompts/list+get, resources/list+read, and resource-templates/list never threaded
the OBO subject token, so those operations failed closed (401 / empty) on a
token_exchange server. Thread the caller's bearer as the subject for those paths
too, gated on the token_exchange mode via a shared _obo_subject_token helper.
* fix(mcp): keep the OBO/authz_code resolver credential authoritative; centralize OpenAPI strip
A guardrail (e.g. MCPJWTSigner), static_headers, or any other injected Authorization could
shadow the resolver-owned credential for token_exchange / authorization_code servers, so the
upstream would receive e.g. the signer's JWT instead of the exchanged token and reject it. In
_create_mcp_client the resolver-owned credential now wins: a conflicting header is dropped and
the minted/stored token reaches upstream. No behavior change for none/passthrough/static modes,
where an injected Authorization still wins as before.
The OpenAPI/local _request_extra_headers forwarder gated its Authorization strip on
has_client_credentials only, so an OpenAPI-backed token_exchange server with
extra_headers:[Authorization] forwarded the raw subject token upstream and never exchanged. It
now uses the centralized _should_strip_caller_authorization so it matches the managed paths.
* feat(mcp): RFC 9728 challenge for token_exchange (OBO) unauthorized
OBO previously returned an opaque 401 (Bearer error="invalid_request") with no discovery
info, and any IdP exchange failure collapsed to a retryable 503. Now an OBO server behaves like
a standards-compliant OAuth resource server:
- A missing/rejected subject token returns the RFC 9728 / RFC 6750 challenge: 401 +
WWW-Authenticate: Bearer resource_metadata="...", error="invalid_token", so a spec-compliant
MCP client can discover the IdP, SSO, and retry with a fresh subject token.
- The protected-resource metadata for a token_exchange server advertises the JWT-auth issuer(s)
(JWT_ISSUER / litellm_jwtauth.issuers) as authorization_servers -- the IdP that issues and
validates the subject -- instead of the gateway.
- An IdP 4xx (subject rejected) is now a non-retryable 401 (the challenge) instead of a 503, so a
caller with a dead token re-authenticates rather than looping; 5xx/transport stays retryable 503.
* fix(mcp): emit the OBO RFC 9728 challenge preemptively so a no-subject client can discover the IdP
A token_exchange server's tools are not discoverable without a subject token (list is lenient ->
empty), and a tool-call-time 401 is wrapped into a JSON-RPC error so the WWW-Authenticate header is
lost. So a cold-start client never saw the challenge and could not start discovery. Add a
token_exchange branch to the preemptive-401: a no-subject connect to an OBO server now returns
401 + WWW-Authenticate: Bearer resource_metadata=..., error="invalid_token" at the transport level,
so a spec-compliant client discovers the IdP (the PRM advertises the JWT-auth issuer), SSOs, and
retries with a subject token. Verified live on the per-server endpoint; the with-subject connect
still proceeds (no challenge).
(Also formats two lines from earlier commits in this stack.)
* refactor(mcp): inject root_path into the OBO/OAuth challenge edge
The adapter's raise_user_oauth_challenge and raise_token_exchange_challenge
reached into os.getenv("SERVER_ROOT_PATH") via get_server_root_path(), a
hidden ambient read in a module that is meant to be a pure edge. That coupling
made the preemptive-challenge test order-dependent under xdist: a sibling test
sets SERVER_ROOT_PATH at import without cleanup, leaking the prefix into the
challenge URL and failing the exact-match assertion.
Resolve the root path at the imperative-shell call sites and pass it in
keyword-only, so both challenge builders become pure functions of their inputs.
Extract the shared resource_metadata path construction into a single
oauth_protected_resource_path helper, collapsing the duplicated prefix/name
logic the two functions carried.
Also reduce _create_mcp_client below the strict complexity ceiling by extracting
the v2 credential resolution into _resolve_v2_auth, and extract the OBO
protected-resource-metadata branch into _obo_protected_resource_response (which
shipped without coverage) so discovery can be unit-tested directly.
Tests are now hermetic: the adapter tests pass root_path as a real input rather
than monkeypatching the environment, the stale-session preemptive test asserts
structural invariants instead of the exact prefixed URL, and five new tests
cover the OBO PRM issuer branch end to end.
* feat(mcp): OBO cache-key tenant isolation, reactive 401 retry, v1-parity logs
From a pass over the OBO behavior contract. Three changes to the
token_exchange arm, none of which alters any other auth mode.
The exchanged-token cache key now folds in the caller's tenant alongside
the subject token and exchange config, so two tenants presenting the same
opaque token can never share a cache entry; cross-tenant isolation is
structural rather than incidental to subject-token uniqueness. tenant_id is
threaded from the resolver's Subject; it is keyword-only with an empty
default so the no-tenant case and the existing call sites are unchanged.
The tool-call path gains one reactive retry. When an upstream rejects the
injected token with a 401/403, the gateway invalidates the cached exchange,
re-mints once through the IdP by rebuilding the client, and retries the call
exactly once before surfacing the upstream error, so a token revoked or
rotated upstream mid-TTL self-heals without an infinite loop. It is gated
strictly to oauth2_token_exchange; passthrough, authorization_code,
client_credentials, api_key, and none keep their single-call behavior.
MCPClient.call_tool gains a raise_on_error flag (mirroring list_tools) so
the path can tell an upstream 401 apart from an ordinary tool error and
avoid re-running a non-idempotent tool on a non-auth failure.
The exchanger also emits the v1-parity log lines it had dropped (attempt
with server, endpoint and audience; success; cache hit), while never
logging the form, subject token, secret, or minted token.
* fix(mcp): fail closed with 412 when a token_exchange server has no endpoint
A true token_exchange (OBO) server must use only an explicitly configured
token endpoint; it must never guess an IdP or silently fall back to a weaker
source. Previously an OBO server with client credentials but no
token_exchange_endpoint/token_url deferred to v1, which no-op'd and let the
request connect to the upstream with no credential (an upstream 401 rather
than a clear gateway error).
Now such a server is owned by the v2 arm: _token_exchange_spec builds the spec
even when the endpoint is absent, and the exchanger fails closed with a
precondition_required error that maps to HTTP 412 before any upstream or IdP
call, with the caller's subject token never sent anywhere. A missing
client_id/secret still maps to misconfigured (500); a present-but-rejected
subject still maps to 401; an unreachable IdP still maps to 503. The no-subject
case keeps its existing 401 RFC 9728 challenge.
* feat(mcp): log a refused non-Bearer token_type in the OBO exchange
* fix(mcp): surface OBO/authorization_code list-time 401 as a challenge instead of masking it
* feat(mcp): classify RFC 6749 gateway-fault token-exchange errors as 500, not a caller 401
* test(mcp): absorb fixture uses 500 now that 401/403 are challenge-class at list time
* style(mcp): PEP 604 union in the OBO retry signature to keep the UP007 budget flat
|
||
|---|---|---|
| .cargo | ||
| .circleci | ||
| .devcontainer | ||
| .githooks | ||
| .github | ||
| .semgrep/rules | ||
| backend | ||
| ci_cd | ||
| cookbook | ||
| db_scripts | ||
| deploy | ||
| dist | ||
| docker | ||
| enterprise | ||
| examples | ||
| gateway | ||
| helm/litellm | ||
| litellm | ||
| litellm-proxy-extras | ||
| litellm-rust | ||
| migrations | ||
| packaging/homebrew | ||
| scripts | ||
| terraform/litellm | ||
| tests | ||
| ui | ||
| .dockerignore | ||
| .env.example | ||
| .flake8 | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitguardian.yaml | ||
| .gitignore | ||
| .npmrc | ||
| AGENTS.md | ||
| ARCHITECTURE.md | ||
| basedpyright-code-budget.json | ||
| CLAUDE.md | ||
| codecov.yaml | ||
| CONTRIBUTING.md | ||
| cosign.pub | ||
| docker-compose.hardened.yml | ||
| docker-compose.yml | ||
| Dockerfile | ||
| GEMINI.md | ||
| LICENSE | ||
| license_cache.json | ||
| Makefile | ||
| mcp_servers.json | ||
| model_prices_and_context_window.json | ||
| osv-scanner.toml | ||
| package-lock.json | ||
| package.json | ||
| policy_templates.json | ||
| prometheus.yml | ||
| provider_endpoints_support.json | ||
| proxy_server_config.yaml | ||
| pyproject.toml | ||
| pyrightconfig.json | ||
| qa_sticky_session.sh | ||
| README.md | ||
| render.yaml | ||
| ruff-strict-budget.json | ||
| ruff-strict.toml | ||
| ruff.toml | ||
| schema.prisma | ||
| security.md | ||
| taplo.toml | ||
| type-discipline-budget.json | ||
| 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 — set protocolVersion to 1.0 or 0.3 per agent
Step 2. Call Agent via A2A SDK (requires a2a-sdk>=1.1.0)
import httpx
from a2a.client import A2ACardResolver, ClientConfig, ClientFactory
from a2a.types import Message, Part, Role, SendMessageRequest
from a2a.utils.constants import TransportProtocol
from uuid import uuid4
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, timeout=60.0) as http_client:
resolver = A2ACardResolver(httpx_client=http_client, base_url=base_url)
agent_card = await resolver.get_agent_card()
config = ClientConfig(
httpx_client=http_client,
streaming=False,
supported_protocol_bindings=[TransportProtocol.JSONRPC, TransportProtocol.HTTP_JSON],
)
client = ClientFactory(config).create(agent_card)
request = SendMessageRequest(
message=Message(
message_id=uuid4().hex,
role=Role.ROLE_USER,
parts=[Part(text="Hello!")],
)
)
async for event in client.send_message(request):
populated = event.ListFields()
if populated and populated[0][0].name in ("message", "msg"):
print("".join(getattr(p, "text", "") or "" for p in populated[0][1].parts))
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.
Deploy on AWS or GCP with Terraform
Run the LiteLLM proxy as a production-ready componentized stack (gateway, backend, UI on separate services; managed Postgres + Redis + object store) using the published Terraform modules. Both modules are on the public Terraform Registry — no auth needed.
AWS — ECS Fargate + Aurora + ElastiCache + ALB
— opens an in-browser shell, already authenticated to your AWS account. Once inside, run:
git clone https://github.com/BerriAI/litellm.git
cd litellm/terraform/litellm/aws/examples/default
cp terraform.tfvars.example terraform.tfvars # edit region/tenant/env
terraform init && terraform apply
Or call the module from your own root config:
# main.tf
terraform {
required_version = ">= 1.6.0"
required_providers {
aws = { source = "hashicorp/aws", version = "~> 5.60" }
}
}
provider "aws" {
region = "us-west-2"
}
module "litellm" {
source = "BerriAI/litellm/aws"
version = "~> 1.89"
region = "us-west-2"
azs = ["us-west-2a", "us-west-2b"]
tenant = "acme"
env = "prod"
# Production: provide an ACM cert. Without one, set allow_plaintext_alb = true
# (dev/trial only).
# acm_certificate_arn = "arn:aws:acm:us-west-2:111122223333:certificate/..."
allow_plaintext_alb = true
}
output "litellm_url" {
value = module.litellm.alb_dns_name
}
terraform init
terraform apply
Provider API keys live in AWS Secrets Manager; reference ARNs via gateway_extra_secrets. Full input list and architecture diagram on the registry page.
GCP — Cloud Run + Cloud SQL + Memorystore + HTTPS LB
Real 1-click. Opens Cloud Shell, clones this repo, and walks you through terraform apply via a built-in DeployStack tutorial — pick the project, the tutorial sets up the Artifact Registry remote repo, writes terraform.tfvars from your answers, and runs apply.
To call the module from your own config instead, Cloud Run can't pull from ghcr.io directly, so first set up a one-time Artifact Registry remote repo backed by GHCR:
gcloud artifacts repositories create litellm \
--location=us-central1 \
--repository-format=docker \
--mode=remote-repository \
--remote-docker-repo=https://ghcr.io \
--project=my-gcp-project
Then:
# main.tf
terraform {
required_version = ">= 1.6.0"
required_providers {
google = { source = "hashicorp/google", version = "~> 6.10" }
google-beta = { source = "hashicorp/google-beta", version = "~> 6.10" }
}
}
provider "google" { project = "my-gcp-project"; region = "us-central1" }
provider "google-beta" { project = "my-gcp-project"; region = "us-central1" }
module "litellm" {
source = "BerriAI/litellm/google"
version = "~> 1.89"
project_id = "my-gcp-project"
region = "us-central1"
tenant = "acme"
env = "prod"
# Replace my-gcp-project with your GCP project ID (same value as project_id above).
image_registry = "us-central1-docker.pkg.dev/my-gcp-project/litellm/berriai"
# Production: provide DNS already pointing at the LB IP for Google-managed certs.
# Without one, set allow_plaintext_lb = true (dev/trial only).
# lb_domains = ["proxy.example.com"]
allow_plaintext_lb = true
}
output "litellm_url" {
value = module.litellm.load_balancer_url
}
terraform init
terraform apply
Provider API keys live in Secret Manager; reference resource IDs (e.g. projects/my-gcp-project/secrets/openai-api-key) via gateway_extra_secrets. Full input list and architecture diagram on the registry page.
Both stacks include
- The full componentized split (gateway / backend / UI as independent services)
- Managed Postgres (writer + reader) and Redis
- Versioned object store for proxy state + file uploads
- An auto-generated
LITELLM_MASTER_KEYin your cloud's secret manager - A one-off migration job that runs
prisma migrate deploybefore the proxy starts - The same
proxy_configsurface as the Helm chart — pass YAML as a typed map
The Terraform modules live at terraform/litellm/aws/ and terraform/litellm/gcp/ in this repo; the registry entries are read-only mirrors updated on each release.
Run in Developer Mode
Services
- Setup .env file in root
- Run dependent 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.
📖 Contributing to documentation? The LiteLLM docs have moved to a separate repository: BerriAI/litellm-docs. Please open doc PRs there. Docs are served at docs.litellm.ai.
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
