API - First x402 endpoint

app.ts

@@ -4,6 +4,7 @@ import cors from "cors";
 import routes from "./routes";
 import bodyParser from "body-parser";
 import dotenv from "dotenv";
+import { createPaymentMiddleware } from "./lib/x402/paymentMiddleware";
 
 dotenv.config();
 
@@ -15,6 +16,7 @@ app.use(express.urlencoded({ extended: false, limit: "10mb" }));
 app.use(cors());
 app.use(bodyParser.urlencoded({ extended: false }));
 app.use(bodyParser.json());
+app.use(createPaymentMiddleware());
 app.use("/api", routes);
 
 app.listen(port, () => {

lib/x402/paymentMiddleware.ts

@@ -0,0 +1,36 @@
+import { paymentMiddleware } from "x402-express";
+import type { RequestHandler } from "express";
+
+const RECEIVING_WALLET_ADDRESS = "0x749B7b7A6944d72266Be9500FC8C221B6A7554Ce";
+const FACILITATOR_URL = "https://x402.org/facilitator";
+
+type RoutesConfig = Parameters<typeof paymentMiddleware>[1];
+
+const routeConfig = {
+  "GET /api/image/generate": {
+    price: "$0.001",
+    network: "base-sepolia" as const,
+    config: {
+      description: "Generate images using AI",
+      inputSchema: {
+        type: "object" as const,
+        properties: {
+          location: { type: "string" as const, description: "City name" },
+        },
+      },
+      outputSchema: {
+        type: "object" as const,
+        properties: {
+          weather: { type: "string" as const },
+          temperature: { type: "number" as const },
+        },
+      },
+    },
+  },
+} as RoutesConfig;
+
+export const createPaymentMiddleware = (): RequestHandler => {
+  return paymentMiddleware(RECEIVING_WALLET_ADDRESS, routeConfig, {
+    url: FACILITATOR_URL,
+  });
+};

package.json

@@ -18,6 +18,7 @@
   "dependencies": {
     "@browserbasehq/stagehand": "^1.10.1",
     "@coinbase/coinbase-sdk": "^0.21.0",
+    "@coinbase/x402": "^0.7.3",
     "@langchain/anthropic": "^0.3.15",
     "@langchain/core": "^0.3.42",
     "@langchain/langgraph": "^0.2.55",
@@ -46,10 +47,11 @@
     "prettier": "^3.4.1",
     "socket.io": "^4.8.1",
     "stripe": "^18.5.0",
-    "tsconfig-paths": "^4.2.0",
     "ts-node": "^10.9.2",
+    "tsconfig-paths": "^4.2.0",
     "uuid": "^11.0.5",
     "viem": "^2.37.5",
+    "x402-express": "^0.7.3",
     "zod": "^4.1.12"
   },
   "devDependencies": {