@nwire/express

Express-backed HTTP adopter — same wires as @nwire/koa, different runtime.

pnpm add @nwire/express @nwire/app @nwire/endpoint @nwire/wires

express@^4 || ^5 is a peer dep.

Two integration modes

1. Drive Nwire as the HTTP server (Adapter mode)

import { createApp } from "@nwire/app";
import { endpoint } from "@nwire/endpoint";
import { post } from "@nwire/wires/http";
import { expressAdapter } from "@nwire/express";
import { z } from "zod";

const app = createApp({ appName: "api" });
app.wire(post("/hello", { body: z.object({ name: z.string() }) }), async (input) => ({
  message: `Hello, ${input.name}!`,
}));

await endpoint("api", { port: 3000 })
  .use(expressAdapter({ prefix: "/api" }))
  .mount(app)
  .run();

2. Mount Nwire wires inside an existing Express app

When you already run Express (or NestJS, which uses Express under the hood), nwireToExpressRouter extracts wired routes as an Express Router you mount alongside legacy handlers. Migration without rewrite.

import express from "express";
import { createApp } from "@nwire/app";
import { nwireToExpressRouter } from "@nwire/express";

const legacy = express();
legacy.get("/legacy", legacyHandler);

const nwireApp = createApp({ appName: "orders" });
nwireApp.wire(/* ... */);
await nwireApp.start();

legacy.use("/api/nwire", nwireToExpressRouter(nwireApp));
legacy.listen(3000);

The router handles its own JSON body-parsing (bodyParser: false opts out) so it works whether Express has body-parser globally or not. See examples/nest-interop for the full Nwire-inside-NestJS pattern.

Adopter config

expressAdapter({
  port: 3000, // 0 = ephemeral; .port() returns the bound port
  host: "0.0.0.0",
  prefix: "/api",
  middleware: [helmet(), morgan("combined")],
  logger: myLogger,
});

Bridging middleware

fromExpressMiddleware(mw) wraps an Express middleware so it can be passed in httpKoa({ middleware: [...] }) — useful when an Express-only middleware (e.g., a vendored auth check) needs to run inside a Koa-backed adopter.

Related

• @nwire/koa — Koa-backed sibling adopter
• @nwire/endpoint — the lifecycle host
• examples/nest-interop — Nwire inside NestJS