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    X402 Api Paywall

    6

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

    Free

    4 usesSecurity scanned
    x402-api-paywall

    x402-api-paywall

    Example session with this skill installed

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

    • Read your context and instructions
    • Compiled the x402-api-paywall

    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.

    Connects securely to your tools. The creator never sees your data.

    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.

    • Only supports FastAPI and Express.
    • Requires external facilitator for server-side verification.
    • Local tests use mocked proofs.

    Open docs

    How to use

    1. 1

      Connect your agent to the Agensi MCP

      Copy the prompt and paste it into Claude, ChatGPT, Cursor or any agent that supports MCP. It sets up the connection for you. Manual setup

    2. 2

      Sign in to Agensi

      Your agent shows a sign-in link. Sign in and click Allow.

    3. 3

      Ask for what you need

      Your agent loads this skill and uses it on your task. It always asks before any payment.

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    4 uses

    Times used to date

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    Trust & safety

    Security scan

    Security scan passed 29 days ago

    • Free with an Agensi account

    Software
    Python

    Permissions

    Environment Variables
    Listed4 months ago
    Updated29 days ago

    What's inside

    Frequently Asked Questions

    This skill automates the integration of the HTTP 402 "Payment Required" protocol into your API, allowing you to charge AI agents micro-amounts of stablecoins per request without building a billing system from scratch.

    It is specifically designed for FastAPI (Python) and Express (Node.js) frameworks, providing native-style middleware and dependencies for these environments.

    The skill focuses on stablecoin ecosystems, specifically USDC, and is optimized for low-fee networks like Base to ensure micropayments remain cost-effective for both providers and consumers.

    You will receive a specialized AI agent workflow capable of generating, configuring, and troubleshooting the x402 middleware logic within your specific codebase.

    No, the skill is designed to be non-destructive; it allows you to wrap specific routes in a paywall while leaving your public endpoints and core business logic untouched.

    The skill implements a secure server-side handshake that verifies cryptographically signed payment proofs against dedicated facilitators before any sensitive data is returned by your API.

    New in APIs & Backend

    Free