https://app.trynito.ai; it reaches POST /v1/messages and POST /v1/messages/count_tokens. Or point an OpenAI-style client at Chat Completions and adapt the shape differences in the mapping notes. Both with code: Anthropic SDK Drop-in.
Through Chat Completions
GET /v1/models. The full Messages field list is in the Messages reference.
Privacy
The level travels with the model.:confidential model IDs work on both Chat Completions and Messages. Encrypted runs on Chat Completions only, with extra headers; the Messages facade rejects :encrypted IDs. See Privacy Levels.
Errors
- An Anthropic model name. Replace it with a catalog ID.
- A top-level
systemstring on Chat Completions. Move it intomessages.
Related
SDKs
Overview.
Anthropic SDK Drop-in
Quickstart.
Mapping Notes
Field by field.
OpenAI Base URL Swap
The OpenAI SDK.
Chat Completions
The endpoint.
Privacy Levels
The four levels.

