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    X402 Api Paywall

    by Nex AI

    Add stablecoin micropayment paywalls to FastAPI and Express routes using the HTTP 402 standard.

    Updated Jun 2026
    Security scanned

    $99

    · or 495 credits

    30-day refund guarantee

    Secure checkout via Stripe

    Included in download

    • Monetize specific high-cost API endpoints for AI agent consumption
    • Enforce per-request billing without managing complex user accounts
    • env_vars automation included
    • Instant install

    Sample input

    Add an x402 paywall to the /generate-image route in my FastAPI app. Use Base Sepolia and charge 0.10 USDC.

    Sample output

    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.

    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.

    Use Cases

    • Monetize specific high-cost API endpoints for AI agent consumption
    • Enforce per-request billing without managing complex user accounts
    • Integrate standard HTTP 402 handshakes into existing Node or Python backends
    • Automate the setup of secure, server-side payment proof verification

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    Security Scanned

    Passed automated security review

    Permissions

    Environment Variables

    File Scopes

    x402-api-paywall/**

    Tags

    monetization
    fastapi
    express
    web3
    api-security
    Documentation

    Creator

    Nex AI

    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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