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	Id for this request	✅
x-litellm-model-id	string	Deployment id (model_info.id)
x-litellm-model-api-base	string	API base URL	✅
x-litellm-version	string	LiteLLM version
x-litellm-model-group	string	Routed model_list[].model_name (client model)

Example

model_list:
  - model_name: my-chat-model          # clients call this
    litellm_params:
      model: gpt-4o-mini               # LiteLLM calls this upstream
    model_info:
      id: "7c9f2a1b3d8e4f0a2c6b5d9e1f3a7b8c"   # optional; auto-generated if omitted

Header	Example	Notes
x-litellm-model-group	my-chat-model	model_name / request model; not litellm_params.model.
x-litellm-model-id	7c9f2a1b3d8e4f0a2c6b5d9e1f3a7b8c	Which deployment row; use with /v1/model/info?litellm_model_id=....
Response body model	often my-chat-model	Often restamped to match the client; upstream id stays in config.

More examples (illustrative)

Header	Example	Meaning
x-litellm-response-cost	0.000214	This call (USD).
x-litellm-key-spend	12.847	Key total after this call.
x-litellm-response-duration-ms	842.3	Proxy end-to-end (ms).
x-litellm-overhead-duration-ms	15.1	LiteLLM overhead (ms).
x-litellm-attempted-retries	0	Retries.
x-litellm-attempted-fallbacks	1	Fallbacks to another deployment.
x-litellm-call-id	019b2c4d-e5f6-7890-abcd-ef1234567890	Logs / tracing.
x-litellm-version	1.55.3	Version.
x-litellm-model-api-base	https://api.openai.com/v1	Provider base (no query string).

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