--- title: "Anthropic Passthrough" url: "/docs/pass_through/anthropic_completion" canonical_url: "https://docs.litellm.ai/docs/pass_through/anthropic_completion" type: "docs" last_updated: "2026-10-09" summary: "Pass-through endpoints for Anthropic - call provider-specific endpoint, in native format (no translation)." related: - "/docs/pass_through/intro" - "/docs/pass_through/assembly_ai" --- # Anthropic Passthrough > Index of all LiteLLM docs: https://docs.litellm.ai/llms.txt Pass-through endpoints for Anthropic - call provider-specific endpoint, in native format (no translation). | Feature | Supported | Notes | |-------|-------|-------| | Cost Tracking | ✅ | supports all models on `/messages`, `/v1/messages/batches` endpoint | | Logging | ✅ | works across all integrations | | End-user Tracking | ✅ | Prometheus `end_user` label is off by default; enable via `litellm.enable_end_user_cost_tracking_prometheus_only`| | Streaming | ✅ | | Just replace `https://api.anthropic.com` with `LITELLM_PROXY_BASE_URL/anthropic` #### **Example Usage** **curl** ```bash curl --request POST \ --url http://0.0.0.0:4000/anthropic/v1/messages \ --header 'accept: application/json' \ --header 'content-type: application/json' \ --header "Authorization: bearer sk-anything" \ --data '{ "model": "claude-sonnet-5", "max_tokens": 1024, "messages": [ {"role": "user", "content": "Hello, world"} ] }' ``` **Anthropic Python SDK** ```python from anthropic import Anthropic # Initialize client with proxy base URL client = Anthropic( base_url="http://0.0.0.0:4000/anthropic", # /anthropic api_key="sk-anything" # proxy virtual key ) # Make a completion request response = client.messages.create( model="claude-sonnet-5", max_tokens=1024, messages=[ {"role": "user", "content": "Hello, world"} ] ) print(response) ``` Supports **ALL** Anthropic Endpoints (including streaming). [**See All Anthropic Endpoints**](https://docs.anthropic.com/en/api/messages) ## Quick Start Let's call the Anthropic [`/messages` endpoint](https://docs.anthropic.com/en/api/messages) 1. Add Anthropic API Key to your environment ```bash export ANTHROPIC_API_KEY="" ``` 2. Start LiteLLM Proxy ```bash litellm # RUNNING on http://0.0.0.0:4000 ``` 3. Test it! Let's call the Anthropic /messages endpoint ```bash curl http://0.0.0.0:4000/anthropic/v1/messages \ --header "x-api-key: $LITELLM_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "content-type: application/json" \ --data \ '{ "model": "claude-sonnet-5", "max_tokens": 1024, "messages": [ {"role": "user", "content": "Hello, world"} ] }' ``` ## Examples Anything after `http://0.0.0.0:4000/anthropic` is treated as a provider-specific route, and handled accordingly. Key Changes: | **Original Endpoint** | **Replace With** | |------------------------------------------------------|-----------------------------------| | `https://api.anthropic.com` | `http://0.0.0.0:4000/anthropic` (LITELLM_PROXY_BASE_URL="http://0.0.0.0:4000") | | `bearer $ANTHROPIC_API_KEY` | `bearer anything` (use `bearer LITELLM_VIRTUAL_KEY` if Virtual Keys are setup on proxy) | ### **Example 1: Messages endpoint** #### LiteLLM Proxy Call ```bash curl --request POST \ --url http://0.0.0.0:4000/anthropic/v1/messages \ --header "x-api-key: $LITELLM_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "content-type: application/json" \ --data '{ "model": "claude-sonnet-5", "max_tokens": 1024, "messages": [ {"role": "user", "content": "Hello, world"} ] }' ``` #### Direct Anthropic API Call ```bash curl https://api.anthropic.com/v1/messages \ --header "x-api-key: $ANTHROPIC_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "content-type: application/json" \ --data \ '{ "model": "claude-sonnet-5", "max_tokens": 1024, "messages": [ {"role": "user", "content": "Hello, world"} ] }' ``` ### **Example 2: Token Counting API** #### LiteLLM Proxy Call ```bash curl --request POST \ --url http://0.0.0.0:4000/anthropic/v1/messages/count_tokens \ --header "x-api-key: $LITELLM_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "anthropic-beta: token-counting-2024-11-01" \ --header "content-type: application/json" \ --data \ '{ "model": "claude-sonnet-5", "messages": [ {"role": "user", "content": "Hello, world"} ] }' ``` #### Direct Anthropic API Call ```bash curl https://api.anthropic.com/v1/messages/count_tokens \ --header "x-api-key: $ANTHROPIC_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "anthropic-beta: token-counting-2024-11-01" \ --header "content-type: application/json" \ --data \ '{ "model": "claude-sonnet-5", "messages": [ {"role": "user", "content": "Hello, world"} ] }' ``` ### **Example 3: Batch Messages** #### LiteLLM Proxy Call ```bash curl --request POST \ --url http://0.0.0.0:4000/anthropic/v1/messages/batches \ --header "x-api-key: $LITELLM_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "anthropic-beta: message-batches-2024-09-24" \ --header "content-type: application/json" \ --data \ '{ "requests": [ { "custom_id": "my-first-request", "params": { "model": "claude-sonnet-5", "max_tokens": 1024, "messages": [ {"role": "user", "content": "Hello, world"} ] } }, { "custom_id": "my-second-request", "params": { "model": "claude-sonnet-5", "max_tokens": 1024, "messages": [ {"role": "user", "content": "Hi again, friend"} ] } } ] }' ``` #### Direct Anthropic API Call ```bash curl https://api.anthropic.com/v1/messages/batches \ --header "x-api-key: $ANTHROPIC_API_KEY" \ --header "anthropic-version: 2023-06-01" \ --header "anthropic-beta: message-batches-2024-09-24" \ --header "content-type: application/json" \ --data \ '{ "requests": [ { "custom_id": "my-first-request", "params": { "model": "claude-sonnet-5", "max_tokens": 1024, "messages": [ {"role": "user", "content": "Hello, world"} ] } }, { "custom_id": "my-second-request", "params": { "model": "claude-sonnet-5", "max_tokens": 1024, "messages": [ {"role": "user", "content": "Hi again, friend"} ] } } ] }' ``` :::note[Configuration Required for Batch Cost Tracking] For batch passthrough cost tracking to work properly, you need to define the Anthropic model in your `proxy_config.yaml`: ```yaml model_list: - model_name: claude-sonnet-5 # or any alias litellm_params: model: anthropic/claude-sonnet-5 api_key: os.environ/ANTHROPIC_API_KEY ``` This ensures the polling mechanism can correctly identify the provider and retrieve batch status for cost calculation. ::: ## Advanced Pre-requisites - [Setup proxy with DB](../proxy/virtual_keys.md#setup) Use this, to avoid giving developers the raw Anthropic API key, but still letting them use Anthropic endpoints. ### Use with Virtual Keys 1. Setup environment ```bash export DATABASE_URL="" export LITELLM_MASTER_KEY="" export COHERE_API_KEY="" ``` ```bash litellm # RUNNING on http://0.0.0.0:4000 ``` 2. Generate virtual key ```bash curl -X POST 'http://0.0.0.0:4000/key/generate' \ -H "Authorization: Bearer $LITELLM_API_KEY" \ -H 'Content-Type: application/json' \ -d '{}' ``` Expected Response ```bash { ... "key": "sk-" } ``` 3. Test it! ```bash curl --request POST \ --url http://0.0.0.0:4000/anthropic/v1/messages \ --header 'accept: application/json' \ --header 'content-type: application/json' \ --header "Authorization: bearer $LITELLM_API_KEY" \ --data '{ "model": "claude-sonnet-5", "max_tokens": 1024, "messages": [ {"role": "user", "content": "Hello, world"} ] }' ``` ### Send `litellm_metadata` (tags, end-user cost tracking) **curl** ```bash curl --request POST \ --url http://0.0.0.0:4000/anthropic/v1/messages \ --header 'accept: application/json' \ --header 'content-type: application/json' \ --header "Authorization: bearer sk-anything" \ --data '{ "model": "claude-sonnet-5", "max_tokens": 1024, "messages": [ {"role": "user", "content": "Hello, world"} ], "litellm_metadata": { "tags": ["test-tag-1", "test-tag-2"], "user": "test-user" # track end-user/customer cost } }' ``` **Anthropic Python SDK** ```python from anthropic import Anthropic client = Anthropic( base_url="http://0.0.0.0:4000/anthropic", api_key="sk-anything" ) response = client.messages.create( model="claude-sonnet-5", max_tokens=1024, messages=[ {"role": "user", "content": "Hello, world"} ], extra_body={ "litellm_metadata": { "tags": ["test-tag-1", "test-tag-2"], "user": "test-user" # track end-user/customer cost } }, ## OR## metadata={ # anthropic native param - https://docs.anthropic.com/en/api/messages "user_id": "test-user" # track end-user/customer cost } ) print(response) ``` ## Related pages - [Why Pass-Through Endpoints?](https://docs.litellm.ai/docs/pass_through/intro.md) - [AssemblyAI](https://docs.litellm.ai/docs/pass_through/assembly_ai.md)