Gemini Relay

Gemini Relay is a Gemini API proxy on Vercel (Next.js App Router) for regions where direct Gemini access is slow or blocked, plus a browser streaming playground for debugging.

Try it: gemini-relay-proxy.vercel.app/chat (demo only)

Important notes

• Custom domain required for production. Prefer DNS in a region that can reach Google Gemini. Do not rely on *.vercel.app in production. If needed, front the service with a jump host or another edge proxy (e.g. CF).
• Use your own Gemini API key. Do not share or reuse others’ keys.
• Multiturn messages must end with role: user (or a function response). If the first message is not user, the proxy drops it; if the last is not user, the request is rejected.
• Auth paths: /api/v1, /api/v1beta, /api/v1beta2 only.
  • Passthrough: ?key= or x-goog-api-key with your Gemini key.
  • Proxy mode: headers from PROXY_AUTH_HEADERS; server injects a key from GEMINI_API_KEYS.
  • Missing credential/path → 401. Proxy mode without GEMINI_API_KEYS → 503. Empty JSON body on POST/PUT/PATCH → 403 (GET needs no body).
• Runs on Next.js App Router Route Handlers (nodejs + Fluid Compute): app/api/v1|v1beta|v1beta2/[...path] → services/gemini/. Successful calls return 200 then stream. maxDuration and business timeout are 120s.
• Model IDs live in the URL (transparent forward), e.g. /api/v1beta/models/{model}:generateContent. Prefer current Stable: gemini-3.5-flash (general) or gemini-3.5-flash-lite (lighter). Playground can Refresh the official model list.
• Debug via Vercel → Logs (or local pnpm dev terminal). Playground / MCP are for debugging; generation still goes through the REST proxy.

Deploy

1. Clone / import the repo and deploy.
2. Attach a custom domain.