Anthropic
Cloud API provider for Claude models via the Anthropic Messages API, a non-OpenAI-compatible backend.
Anthropic provides Claude models through the Messages API at api.anthropic.com. This is the only supported backend that is not OpenAI-compatible; it requires a dedicated adapter.
Configuration
[backend]
name = "anthropic"
url = "https://api.anthropic.com"
model = "claude-sonnet-4-5-20250929"
api_key = "sk-ant-..."Key Differences from OpenAI
| Feature | OpenAI | Anthropic |
|---|---|---|
| Endpoint | /v1/chat/completions |
/v1/messages |
| Auth header | Authorization: Bearer <key> |
x-api-key: <key> |
| Version header | None | anthropic-version: 2023-06-01 |
| System prompt | In messages array | Top-level system field |
| Streaming format | choices[].delta.content |
content_block_delta |
| Required fields | - | max_tokens |
Default Endpoint
POST https://api.anthropic.com/v1/messages