Authentication

All gateway endpoints require an API key. The recommended authentication method is the Authorization header.

Bearer Token

Item	Value
Header	Authorization
Format	Bearer YOUR_API_KEY
Applies to	All public gateway endpoints

curl https://api.llmapi.site/v1/usage \
  -H 'Authorization: Bearer YOUR_API_KEY'

Compatible Headers

The server also accepts these headers for client compatibility:

Header	Example
Authorization	Bearer YOUR_API_KEY
x-api-key	YOUR_API_KEY
x-goog-api-key	YOUR_API_KEY

Use only one authentication method per request. New integrations should use Authorization: Bearer.

API Key Types

When creating an API key in the console, choose the correct binding type:

Type	Binding	Supported endpoints
General API key	General group	Text APIs, model listing, usage queries, and synchronous platform image endpoints.
Task API key	Per-model Task Plans	/v1/tasks, /v1/tasks/events, /v1/tasks/{id}, result asset downloads, queued task cancellation, and OpenAI Images compatible synchronous endpoints.

The bindings are mutually exclusive. See Create API Keys for the full steps.

A Task API key may select a different plan for each model—for example, an economy plan for an image model and a stability plan for a video model. Models without an explicit selection use their own model-specific default plan. API requests do not include a plan parameter, and public model names do not change between plans.

If an explicitly selected plan is disabled, deleted, or no longer supports that model, only that model returns to its own default plan. Selections for other models are unchanged.

Authentication Failure

Interface details:

Item	Value
HTTP status	401
Error type	authentication_error
Trigger	Missing, invalid, or unrecognized API key

Response example:

{
  "type": "error",
  "error": {
    "type": "authentication_error",
    "message": "Invalid API key"
  }
}

Group and Platform Restrictions

Successful authentication does not make every endpoint available.

Key type	Example endpoints	Restrictions
General API key / OpenAI group	/v1/responses, /v1/chat/completions, /v1/images/generations, /v1/images/edits	Tasks require a Task API key.
General API key / Anthropic group	/v1/messages, /v1/messages/count_tokens	OpenAI-specific image endpoints are unavailable.
General API key / Gemini group	/v1beta/models, /v1beta/models/{model}:generateContent	OpenAI-specific image endpoints are unavailable.
Task API key	/v1/tasks, /v1/tasks/events, /v1/images/generations, /v1/images/edits	Only for Task APIs and OpenAI Images compatible synchronous endpoints, not for text or conversation endpoints.

When the platform or key type does not match, the endpoint may return 400, 403, or 404. See the errors page for examples.