Get started

Introduction Quick start Authentication

Using the API

Models Streaming Tool calling Structured outputs Vision Reasoning Prompt caching Anthropic API compatibility Routing and failover

Integrations

OpenAI SDK Vercel AI SDK LangChain Coding tools

Account & billing

API keys Billing Usage and activity Workspaces and members Privacy

Reference

Rate limits Errors API versioning

Migrations

Migrate from OpenAI Migrate from OpenRouter

API reference

Health check GET Chat Completions POST Retrieve key status GET Anthropic Messages POST Models GET

API versioning

Versioning policy.

The API is versioned by URL path: everything lives under /v1. Within a version, changes are backward compatible (new optional fields, new model IDs). Breaking changes are shipped under a new version prefix.

How is this guide?

Errors

Error JSON shape and status codes.

Migrate from OpenAI

Swap base URL and key to move existing code to Vichar.