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POST
Claude Messages Compatible Endpoint
FreeModel exposes an Anthropic Claude Messages-compatible endpoint at POST /v1/messages. Use this page for request shape, headers, and response fields. Looking for product setup (Claude Code, env vars, /status checks)? See the Claude Code integration guide.

Endpoint

Base URL for Anthropic-compatible clients is https://api.freemodel.app (no /v1 suffix on the base when the client appends /v1/messages).

Authentication and headers

Request body

curl example

A successful response has type: "message" and assistant text under content[0].text (or the equivalent content blocks your client expects).

Choosing a model

Call GET /v1/models and pick a text model ID. FreeModel converts Claude Messages requests to the selected model’s serving protocol. Current GPT catalog pages (for example GPT-5.6) list prices per 1M tokens.
Navigation queries such as “freemodel claude” should land on the Claude Code integration. This page is the technical endpoint reference only.