# Chat & Completions (/docs/api/gateway/chat)

The three wire formats that reach `codai`: OpenAI Chat Completions, Anthropic Messages, OpenAI Responses.

All three endpoints route to the same model chain and share auth, rate limits, prompt caching and usage recording. Pick the one your SDK already speaks — the [wire formats guide](../../gateway/wire-formats.mdx) explains the differences and the [headers guide](../../gateway/headers.mdx) covers every `x-codai-*` extension you see below.

<OpenAPIPage document="./openapi/en/gateway.yaml" operations={[{path: '/v1/chat/completions',method: 'post'},{path: '/v1/messages',method: 'post'},{path: '/v1/responses',method: 'post'}]} />