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Response Headers

When you make a request to the proxy, the proxy will return the following headers:

Rate Limit Headers

OpenAI-compatible headers:

Header Type Description
x-ratelimit-remaining-requests Optional[int] The remaining number of requests that are permitted before exhausting the rate limit
x-ratelimit-remaining-tokens Optional[int] The remaining number of tokens that are permitted before exhausting the rate limit
x-ratelimit-limit-requests Optional[int] The maximum number of requests that are permitted before exhausting the rate limit
x-ratelimit-limit-tokens Optional[int] The maximum number of tokens that are permitted before exhausting the rate limit
x-ratelimit-reset-requests Optional[int] The time at which the rate limit will reset
x-ratelimit-reset-tokens Optional[int] The time at which the rate limit will reset

How Rate Limit Headers work

If key has rate limits set

The proxy will return the remaining rate limits for that key.

If key does not have rate limits set

The proxy returns the remaining requests/tokens returned by the backend provider. (LiteLLM will standardize the backend provider's response headers to match the OpenAI format)

If the backend provider does not return these headers, the value will be None.

These headers are useful for clients to understand the current rate limit status and adjust their request rate accordingly.

Latency Headers

Header Type Description
x-litellm-response-duration-ms float Total duration from the moment that a request gets to LiteLLM Proxy to the moment it gets returned to the client.
x-litellm-overhead-duration-ms float LiteLLM processing overhead in milliseconds

Retry, Fallback Headers

Header Type Description
x-litellm-attempted-retries int Number of retry attempts made
x-litellm-attempted-fallbacks int Number of fallback attempts made
x-litellm-max-fallbacks int Maximum number of fallback attempts allowed

Cost Tracking Headers

Header Type Description Available on Pass-Through Endpoints
x-litellm-response-cost float Cost of the API call
x-litellm-key-spend float Total spend for the API key

LiteLLM Specific Headers

Header Type Description Available on Pass-Through Endpoints
x-litellm-call-id string Unique identifier for the API call
x-litellm-model-id string Unique identifier for the model used
x-litellm-model-api-base string Base URL of the API endpoint
x-litellm-version string Version of LiteLLM being used
x-litellm-model-group string Model group identifier

Response headers from LLM providers

LiteLLM also returns the original response headers from the LLM provider. These headers are prefixed with llm_provider- to distinguish them from LiteLLM's headers.

Example response headers:

llm_provider-openai-processing-ms: 256
llm_provider-openai-version: 2020-10-01
llm_provider-x-ratelimit-limit-requests: 30000
llm_provider-x-ratelimit-limit-tokens: 150000000