Express

Capture Express requests, middleware, handlers, responses, and child operations.

Installation


npm install server-devtools express
npm install -D tsx @types/express

TypeScript setup

Create the preloaded initialization module:


import ServerDevTools from "server-devtools";
 
export const devtools = new ServerDevTools({
  auth: {
    username: process.env.SERVER_DEVTOOLS_USERNAME!,
    password: process.env.SERVER_DEVTOOLS_PASSWORD!,
  },
});
 
await devtools.start();

Mount the same instance before your routes:


import express from "express";
import { devtools } from "../server-devtools";
 
const app = express();
app.use(express.json());
app.use((req, res, next) => devtools.middleware(req, res, next));
 
app.get("/users/:id", (req, res) => {
  res.json({ id: req.params.id });
});
 
app.listen(3000);

Run with preload:


npx tsx watch --import ./server-devtools.ts src/main.ts

JavaScript setup

The package also exposes a CommonJS entry point:


const ServerDevTools = require("server-devtools");
 
const devtools = new ServerDevTools({
  auth: {
    username: process.env.SERVER_DEVTOOLS_USERNAME,
    password: process.env.SERVER_DEVTOOLS_PASSWORD,
  },
});
 
module.exports = { devtools };
void devtools.start();

Start with node --import ./server-devtools.js src/main.js, then mount devtools.middleware before routes.

Run and verify

Open http://localhost:3000/_devtools, sign in, and call /users/123. Express middleware and handler spans appear beneath the HTTP request. Request bodies are captured by the Express instrumentation when available.

Troubleshooting

No request: preload the initialization file before importing Express.
No body: ensure a body parser such as express.json() runs and the request has a body.
Duplicate traces: create one SDK instance and share it across the app.