Why Pass-Through Endpoints?

These endpoints are useful for 2 scenarios:

1. Migrate existing projects to litellm proxy. E.g: If you have users already in production with Anthropic's SDK, you just need to change the base url to get cost tracking/logging/budgets/etc.

2. Use provider-specific endpoints E.g: If you want to use Vertex AI's token counting endpoint

How is your request handled?

The request is passed through to the provider's endpoint. The response is then passed back to the client. No translation is done.

Request Forwarding Process

1. Request Reception: LiteLLM receives your request at /provider/endpoint
2. Authentication: Your LiteLLM API key is validated and mapped to the provider's API key
3. Request Transformation: Request is reformatted for the target provider's API
4. Forwarding: Request is sent to the actual provider endpoint
5. Response Handling: Provider response is returned directly to you

Authentication Flow

Key Points:

• Use your LiteLLM API key in requests, not the provider's key
• LiteLLM handles the provider authentication internally
• Same authentication works across all passthrough endpoints

Error Handling

Provider Errors: Forwarded directly to you with original error codes and messages

LiteLLM Errors:

• 401: Invalid LiteLLM API key
• 404: Provider or endpoint not supported
• 500: Internal routing/forwarding errors

Benefits

• Unified Authentication: One API key for all providers
• Centralized Logging: All requests logged through LiteLLM
• Cost Tracking: Usage tracked across all endpoints
• Access Control: Same permissions apply to passthrough endpoints