> ## Documentation Index
> Fetch the complete documentation index at: https://impossibl.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# One API for all AI providers

> A single OpenAI-compatible endpoint that routes to OpenAI, Anthropic, Google, xAI, Z.ai and Azure Foundry models, billed from one prepaid credit balance.

The Impossibl AI API is a single API for all AI providers. It routes to OpenAI, Anthropic,
Google, xAI, Z.ai, and Azure Foundry-hosted models (Llama, Mistral, DeepSeek, …), and
bills you from a **prepaid credit balance**. It speaks the providers' own wire
formats so existing tools work unchanged:

* **`POST /v1/chat/completions`** — OpenAI Chat Completions (drop-in for any OpenAI SDK)
* **`POST /v1/responses`** — OpenAI Responses API
* **`POST /v1/messages`** — Anthropic Messages API (drop-in for the `anthropic` SDK)
* **`POST /v1beta/models/{model}:generateContent`** — Gemini-native generateContent
* **`POST /v1/audio/transcriptions`** — completed-file speech-to-text
* **`POST /v1/images/generations`** — OpenAI Images (image output)

Pick a model with the `provider/model` convention, e.g. `anthropic/claude-sonnet-4-5`.
See `GET /v1/models` for the full list and pricing.

Beyond text, every surface accepts [image input](/docs/vision), Gemini models accept
[audio and video input](/docs/audio-video), and every surface supports
[tool calling](/docs/tool-calling) in relay mode. Chat output is text; images are
generated through [`openai/gpt-image-2`](/docs/image-generation) and completed audio
files are transcribed with [`openai/gpt-transcribe`](/docs/audio-transcription).

## Agent-first

Everything is built so an **agent** can self-serve with no human in the loop:

* Machine docs at [`/llms.txt`](https://api.impossibl.com/llms.txt) and
  [`/openapi.yaml`](https://api.impossibl.com/openapi.yaml).
* Executable agent onboarding declared at
  [`/auth.md`](https://api.impossibl.com/auth.md), with OAuth protected-resource
  metadata at [`/.well-known/oauth-protected-resource`](https://api.impossibl.com/.well-known/oauth-protected-resource).
* `POST /v1/accounts` creates a **funded** account and returns an API key in one call.

There's no dashboard yet — humans sign up the same way, with the two requests in the
quickstart, straight from a terminal.

<Card title="Agent quickstart" href="/docs/agent-quickstart" icon="robot">
  Register a funded account and make your first call in two requests.
</Card>