Framework Recipes

Most frameworks just need basicUsageEventConsumer in a route handler. Express users get the extra benefit of middlewareEventConsumer and the webhook adapter.

Express - Middleware

The middlewareEventConsumer drops into Express's (req, res, next) signature and tracks events automatically:

import { biller } from "./scrawn/biller";

app.use(biller.middlewareEventConsumer({
  extractor: (req) => {
    if (!req.user) return null;
    return {
      userId: req.user.id,
      debit: biller.tag("API_CALL"),
    };
  },
  blacklist: ["/health", "/api/collect-payment"],
}));

See the middleware section for configuration options.

Express - Webhooks

Use toWebRequest() to convert Express's IncomingMessage to the fetch-compatible Request that biller.webhook() expects:

import { toWebRequest } from "@scrawn/core";
import { biller } from "./scrawn/biller";

app.post("/webhooks/scrawn", async (req, res) => {
  const rawBody = JSON.stringify(req.body);
  const event = await biller.webhook(toWebRequest(req, rawBody));
  res.status(200).send("OK");
});

Other frameworks (Next.js, NestJS, tRPC, Fastify, Hono)

The SDK works with any Node.js HTTP framework - call basicUsageEventConsumer directly in your route handlers.

See the usage tracking guide for the full API, error handling guide for error recovery patterns, and webhook verification for inbound webhook handling.