OpenRouter

OpenRouter gives one API, compatible with the OpenAI format, for hundreds of AI models from many providers, including OpenAI, Anthropic, Google, Meta, Mistral and DeepSeek, with automatic fallbacks between providers. Several models are free to use (their ids end in ':free'). Responses are JSON. Free models are limited to 20 requests per minute and 50 per day, or 1,000 per day once you have bought at least 10 credits; other models are paid per token.