Works with the AI tools you already use
X402 Api Paywall
by Nex AI
Add stablecoin micropayment paywalls to FastAPI and Express routes using the HTTP 402 standard.
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See it in action
You say
Add an x402 paywall to the /generate-image route in my FastAPI app. Use Base Sepolia and charge 0.10 USDC.
Your agent does
I've added the x402_middleware.py and updated your /generate-image route.
@app.post("/generate-image", dependencies=[Depends(require_payment)]) async def generate_image(request: ImageRequest): # Protected logic ...
Unauthenticated requests will now receive a 402 Payment Required response.
What you get
About this skill
Turn your API into a Revenue Stream
Modern AI agents need a way to pay for the services they consume. The x402 API Paywall skill enables you to monetize your Express or FastAPI endpoints using the HTTP 402 "Payment Required" standard and stablecoins.
What it does
This skill acts as a specialized developer assistant that integrates a middleware-based paywall into your existing codebase. Instead of manually writing complex web3 verification logic, the skill automatically implements the x402 handshake: it detects missing or invalid payment proofs, returns machine-readable 402 errors with payment requirements, and verifies proof-of-payment on the server side before granting access to your protected routes.
Supported Tools & Frameworks
- FastAPI (Python): Implements via route dependencies for granular control.
- Express (Node.js): Implements via standard middleware mounting.
- Stablecoin Ecosystem: Built for USDC and other assets on networks like Base.
- Verification: Integrates with facilitator services for secure, server-side proof validation.
Why use this over raw prompting?
Implementing a cryptographically secure paywall requires precise handling of headers, status codes, and external verification APIs. This skill understands the specific architecture of the x402 protocol, ensuring you don't leak "free" requests through logic errors or hardcode sensitive wallet information. It follows a non-destructive path, protecting only the routes you choose while keeping your existing business logic and public endpoints intact.
Built by Nex AI. More skills and info at nex-ai.be and slopsome.com.
How to install
Drop the file into your AI Agent. Works with Claude, Cursor, ChatGPT, and 20+ more.
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Creator
Founder of Nex AI. I build production-grade Claude Skills from systems that actually run: multi-tenant SaaS, Telegram agents, Raspberry Pi infrastructure, 3D multiplayer rooms. Every skill ships battle-tested patterns, not theory. 33+ open source skills published, commercial catalog growing.
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