solmate-x402 0.1.0

FastAPI middleware for Coinbase x402 HTTP payment protocol on Base USDC

x402-solana

FastAPI middleware for the Coinbase x402 HTTP payment protocol on Base USDC.

Novel cross-chain primitive: bridges Solana wallet authentication with Coinbase x402 HTTP payments on Base — extracted from Sol Mate Trust API.

Install

pip install x402-solana

Usage

from fastapi import FastAPI, Depends
from x402_solana import require_x402_payment, X402Config, X402PaymentRequired, x402_exception_handler

app = FastAPI()
app.add_exception_handler(X402PaymentRequired, x402_exception_handler)

config = X402Config(
    pay_to="0xYourBaseWalletAddress",
    amount_usdc=0.5,            # $0.50 USDC per request
    description="DM unlock",
    enabled=True,               # Set False to bypass in dev
)

@app.post("/dm/send", dependencies=[Depends(require_x402_payment(config))])
async def send_dm(body: dict):
    return {"status": "sent"}

Flow

Client → POST /dm/send (no X-Payment header)
Server → 402 Payment Required + {x402Version, accepts: [{network, asset, amount, payTo}]}
Client → pays 0.5 USDC on Base via Coinbase facilitator
Client → POST /dm/send (X-Payment: <proof>)
Server → verifies proof via https://x402.org/facilitator/verify
Server → 200 OK (request processed)

Configuration

Field	Default	Description
pay_to	required	Base wallet address to receive USDC
amount_usdc	0.5	Payment amount in USDC
network	"base"	"base" or "base-sepolia"
asset	USDC Base contract	ERC-20 token address
description	"API payment"	Shown in wallet UI
max_timeout_seconds	300	Payment validity window
enabled	True	Set False to bypass (dev/test)

Graceful Degradation

If the Coinbase facilitator is unreachable, requests are allowed through automatically. Set enabled=False for local development.

License

MIT — extracted from Sol Mate Trust API. Built for EasyA × Consensus Miami 2026.