Creating x402 Payment-Protected Servers in Python

Build FastAPI (async) or Flask (sync) servers that protect API endpoints behind Algorand USDC payments using x402 middleware.

Prerequisites

Before using this skill, ensure:

1. Python 3.10+ is installed
2. An Algorand address to receive payments (the payTo address)
3. A facilitator URL -- use https://x402.org/facilitator or run your own
4. Understanding of FastAPI or Flask basics

Core Workflow: Middleware-Based Payment Protection

The middleware intercepts requests to protected routes, checks for payment headers, verifies payments through the facilitator, and settles on success.