API Overview
FastMetal provides an OpenAI-compatible API and Anthropic-compatible API for all models we support. Use your existing tools and libraries with minimal configuration changes.
Authentication
All API requests require authentication using an API key. Include your key in the Authorization header:
Authorization: Bearer YOUR_API_KEYBase URLs
Make requests to the appropriate base URL for your chosen API format:
https://api.fastmetal.ai/v1Supported Endpoints
OpenAI Compatible
/models — List available models /chat/completions — Chat-based completions with conversation history /responses — The Responses API (the format Codex uses) /completions — Traditional text completions
Anthropic Compatible
/messages — Send and receive messages /messages/count_tokens — Count tokens in messages
Platform
/key/info — Check your API key's budget, spend and remaining balance
Rate Limits
Rate limits are determined by your account's budget. Requests are rejected when your spend exceeds your available balance. Monitor your usage on the dashboard to avoid interruptions.
Error Handling
The API returns standard HTTP status codes. Common errors include:
401Invalid or missing API key400Budget exceeded or invalid request429Rate limit exceeded500Internal server error