x402 starters

The shortest working way to charge for an HTTP route, and to pay for one, using the official x402 SDKs. Every file here runs as it is; the only thing you must change is the wallet that gets paid.

x402 revives HTTP 402 Payment Required. Your server answers an unpaid request with 402 and machine-readable terms, the client signs a stablecoin payment, and a facilitator verifies the signature and settles it on-chain. Your server never holds a key and never talks to a chain.

Pick one

Folder	Stack	What it is
express	Node, Express	One paid GET /premium route
hono	Node, Hono	The same route on Hono
next	Next.js App Router	A paid API route
fastapi	Python, FastAPI	The same route in Python
client	Node and Python	Paying for a 402 route from a script or an agent

Run one in a minute

cd express
npm install
export MERCHANT=0xYourWalletAddress      # where the money goes, on Base
npm start
curl -i localhost:3000/premium           # 402 with terms

Then pay it with a client from client, or point any x402 client at it.

The facilitator

These starters use https://pay.neuronto.com as the facilitator: the service that verifies the payer's signature and broadcasts the settlement. It is one line in every file, and any x402 facilitator can take its place:

new HTTPFacilitatorClient({ url: "https://pay.neuronto.com" })

Base mainnet (eip155:8453) is live there. GET https://pay.neuronto.com/supported lists every network, scheme and version it settles right now; a network that cannot settle disappears from that list before it starts refusing, so a server that reads /supported never advertises a price it cannot take.

Testing without spending anything

https://pay.neuronto.com/echo is a live merchant that charges $0.001 and sends it straight back in the same request, so a client can be run end to end for the cost of nothing:

curl -i https://pay.neuronto.com/echo        # a real 402, with real terms

Point any of the clients in client at that URL. The refund is automatic; the gas is not yours.

What you need

• A wallet address to be paid to. Nothing is installed on your side to receive money: payments arrive as USDC transfers to the address you put in MERCHANT.
• For a paying client, a funded key. Never put a real key in a file: every example here reads it from the environment.

Licence

Apache-2.0.