UnoRouter is a usage-billed AI service for SaaS teams that want the big language models in their product without signing up with each vendor. One OpenAI-compatible key covers models from OpenAI, Anthropic, Google, Meta, DeepSeek, Qwen and Mistral, and if a provider goes down the request moves to another one automatically. Developers keep their OpenAI SDK code or use Claude Code, Cline and OpenCode. The code is open source, free models are included, and there is no subscription.