Quickstart

Wrap a handler so paying agents (or anyone with USDC on Base) can call it.

Building the agent side — an agent that consumes paid APIs, with its own wallet, inbox, and vault? That's Mailgent.

1. Create a project

console.loomal.ai → Create a project. You get an API key (loid-...).

In the project's Pay tab, switch Accept payments on — it's off by default on a fresh project.

2. Install the SDK and wrap your handler

npm install @loomal/sdk express

import express from "express";
import { requirePayment } from "@loomal/sdk/paywall/express";

const app = express();
app.set("trust proxy", true);

app.get(
  "/search",
  requirePayment({ amount: "0.05" }),
  (req, res) => res.json({ results: [/* ... */] }),
);

app.listen(3030);

Set LOOMAL_API_KEY=loid-... and run the server. The middleware handles the 402 challenge, verifies the signed retry, settles on Base, and returns the X-Payment-Response header.

Other frameworks:

3. Make a paid request

You need a caller with a few cents of USDC on Base to call your endpoint. The simplest path is to run a working caller from loomal-ai/loomal-pay-examples (clone, install, run).

When the call succeeds, your project's Pay → Activity tab shows the settled payment with an on-chain link.

4. Where to go next

• Full payment flow (raw REST, webhooks, refunds): Accept Payments.
• Working example to clone: Paid Search API.