xPay - Turn any endpoint into a paid microservice

Monetize your endpoints without writing code. xPay is the first no-code platform to help you monetize your endpoint and infrastructure. xPay wraps your existing HTTP endpoints with a trust-minimized pay-per-request proxy powered by x402 microtransactions on Solana (USDC by default). In minutes, your API can accept payments, expose a beautiful marketplace listing with reviews, and even become an MCP server that AI agents can call as first-class tools.

Why this matters

• Own your distribution: No keys to rotate or centralized gatekeepers. Each request proves payment cryptographically.
• Instant settlement: Payments land directly in your wallet with near-zero fees and no custody risk.
• AI-native: Your endpoints instantly become MCP tools, usable by LLM agents with built-in, per-call payments.
• No-code onboarding: Point to your existing API, set a price, pick a token, and share your new paid URL.

---

What you can do with xPay

• Wrap any HTTP endpoint in a paid proxy: https://api.usexpay.xyz/:username/:endpointName
• Set per-call pricing and token (USDC SPL by default; any SPL token address supported)
• Enforce payment via the x402 standard with Faremeter middleware
• List your API in a marketplace with ratings, usage examples, and earnings
• Provide AI agents an MCP server at GET/POST /mcp/:username where each tool = your endpoint

---

How it works (high level)

1. Register an endpoint (creator dashboard or API): name, description, original URL, HTTP method, price, token, optional auth headers, sample I/O.
2. xPay generates a paid proxy URL: e.g. /:username/:endpointName which forwards to your original URL.
3. Faremeter x402 middleware verifies payment on each call, then forwards the request and returns the response.
4. Earnings tracked per endpoint on successful 2xx responses.
5. AI/MCP: xPay builds a per-user MCP server; each endpoint becomes a tool with typed inputs from your sample body.
6. Users and reviews: Consumers can rate endpoints; creators manage profile, endpoints, and monitor balances.

---

Architecture overview

• Backend: Node.js + Express (TypeScript), Drizzle ORM (Postgres), Zod validation, JWT auth, Solana Web3, Faremeter x402 middleware, MCP SDK, Axios proxy, Vercel AI SDK endpoints for text/image examples.
• Frontend: Next.js 15 (App Router), Tailwind + Radix UI, React Query, Coinbase CDP Wallet for signature-based login, polished landing and dashboard UX.
• Storage/Infra: Postgres (DATABASE_URL), optional local uploads for AI image examples, environment-driven configuration.

See module guides:

• Backend README: backend/README.md
• Frontend README: frontend/README.md

---

Quickstart

1. Fill in all required environment variables in the appropriate .env files. Refer to the provided .env.example files in each app for guidance.
2. From the repo root, install all dependencies:

   npm install
   

3. Start all apps in development mode:

   npm run dev
   

4. (Optional) For backend DB migrations, you can still use:

   npm run db:generate && npm run db:migrate
   

5. The backend will default to http://localhost:3000, and the frontend to http://localhost:3001.

---

Key capabilities in depth

x402-powered paywall

Every paid proxy call passes through Faremeter’s x402 middleware:

• Accepts Solana SPL tokens (USDC mint by default)
• Enforces exact per-call pricing
• Attaches resource metadata and description for auditability
• Streams responses after payment verification

Marketplace and reviews

GET /endpoints returns a paginated catalog including average ratings and counts. Creators grow reputation; consumers discover reliable tools.

Dynamic MCP servers

Each user gets an MCP server at /mcp/:username. Tools are synthesized from your registered endpoints:

• Tool descriptions include method and cost
• Input schemas are generated from your sample request body
• Session lifecycle handled via mcp-session-id
• Payment is bypassed for MCP protocol list/initialize calls but enforced for tool invocations

Creator auth (wallet signature → JWT)

Frontend uses Coinbase CDP wallet to sign a message. Backend verifies the signature and issues a JWT for authenticated actions (create/update/delete endpoints, update profile).

---

Production notes

• Run Postgres with backups and TLS.
• Keep JWT_SECRET secure and rotate on schedule.
• Use a dedicated Solana RPC; set SOLANA_RPC_URL.
• Review CORS and rate limits for public routes.
• Prefer mainnet-beta for real payments; use small price increments to test.

---

License

MIT. See LICENSE.md

---

Questions or ideas? Open an issue or PR. We’d love to see what APIs you monetize with xPay.