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

# Use any model from any SDK

> Call an Anthropic model with OpenAI code, or the reverse, with automatic translation

When a routing rule sends a request to a provider that speaks a different format than the caller,
the gateway translates it both ways. Your OpenAI code can call an Anthropic model, and your
Anthropic code can call an OpenAI model, with no change on your side.

## How it works

Set up a [routing rule](/gateway/route-requests) that targets a provider in the other format, for
example routing OpenAI-format traffic to an `anthropic` provider. From then on, the gateway:

* Translates the **request** from the OpenAI Responses API to the Anthropic Messages API, or the reverse.
* Translates the **response** back into the format your client expects.
* Translates **streaming** events the same way, so streaming keeps working.

## What's translated

The common shape of a chat request carries over in both directions:

* Messages and the system prompt.
* The max-tokens setting.
* Tools, tool choice, and tool results.

## Limits

* Content types beyond text, such as images, documents, and web search, are not translated yet. A request that needs them returns **501 Not Implemented**.
* The `azure_openai` format is wire-compatible with `openai`, so traffic between them is never translated.