The Payment Layer for AI.

Scale your x402 payments with institutional-grade compliance and reliability.

// ONE-LINE INTEGRATION

Monetize your API in minutes. x402 v1 and v2 are both supported. Simply use https://facilitator.heurist.xyz as your facilitator URL.

Detailed Examples

import express from "express";
import { paymentMiddleware, x402ResourceServer } from "@x402/express";
import { ExactEvmScheme } from "@x402/evm/exact/server";
import { HTTPFacilitatorClient } from "@x402/core/server";

const server = new x402ResourceServer(
  new HTTPFacilitatorClient({ url: "https://facilitator.heurist.xyz" }),
).register("eip155:8432", new ExactEvmScheme());

app.use(paymentMiddleware(routes, server));

Reliability and Compliance, Built for Scale.

High-Throughput

Scale with confidence. Our transaction management system is built for high-frequency requests.

Multi-Network Support

Address a global audience. One endpoint, multiple ecosystems.

OFAC Compliant

Meet regulatory requirements. Our facilitator automatically screens and blocks transactions from OFAC-sanctioned addresses.

API Free

Eliminate onboarding friction. Integrate in seconds with no API key needed.

Real-Time Observability

Track your onchain revenue with a real-time dashboard to monitor API health, transaction volume, and earnings. (Coming Soon)

Auto-Buyback

Accrue value without intervention. Automatically convert USDC revenue into your native project token on every settlement. (Coming Soon)

Start Building

Start accepting agentic crypto payments in minutes.

Chain

Framework

Payout wallet (payTo)

Install commands

npm i express @x402/express @x402/evm @x402/core

Sample server code

v2: Express (@x402/express) · Base (USDC)

import express from "express";
import { paymentMiddleware, x402ResourceServer } from "@x402/express";
import { ExactEvmScheme } from "@x402/evm/exact/server";
import { HTTPFacilitatorClient } from "@x402/core/server";

const app = express();

// Your receiving wallet address
const payTo = "0xYourReceivingAddress";

// Create facilitator client (testnet)
const facilitatorClient = new HTTPFacilitatorClient({
  url: "https://facilitator.heurist.xyz"
});

// Create resource server and register EVM scheme
const server = new x402ResourceServer(facilitatorClient)
  .register("eip155:8432", new ExactEvmScheme());

app.use(
  paymentMiddleware(
    {
      "GET /weather": {
        accepts: [
          {
            scheme: "exact",
            price: "$0.001", // USDC amount in dollars
            network: "eip155:8432", // Base (CAIP-2 format)
            payTo,
          },
        ],
        description: "Get current weather data for any location",
        mimeType: "application/json",
      },
    },
    server,
  ),
);

app.get("/weather", (req, res) => {
  res.send({
    report: {
      weather: "sunny",
      temperature: 70,
    },
  });
});

app.listen(4021, () => {
  console.log(`Server listening at http://localhost:4021`);
});

The x402 flow: server replies 402 with accepted options ⇒ client retries with X-PAYMENT (base64 JSON) ⇒ server verifies via /verify, settles via /settle, then returns 200. See the seller quickstart and set the facilitator URL to https://facilitator.heurist.xyz.