Let your customers bring the AI subscription they pay for. Think BYOK, but they sign in with the plan they already have instead of pasting a key. ai-oauth-sdk runs the providers' real OAuth flows, the same ones their official CLIs use. The token stays on their device, so you never hold a key or pay for their inference. Eight providers: ChatGPT, Claude, Gemini, Grok, Copilot, Qwen, OpenRouter, Azure. Zero dependencies, MIT. Node, browser, React, Vue, Svelte, Solid, React Native, CLI.