Save Hours on API Testing: Auto-Generate Postman Collections from Your Express.js App 🧪

Shipping a well-documented API can feel like a second job. You build your Express routes, then spend even more time hand-crafting Postman collections so teammates and QA can exercise your endpoints.

What if you could generate that collection automatically—without extra config, manual exports, or tedious copy-pasting?

Enter express-to-postman, a zero-config CLI that introspects your running Express app (JS or TS), bundles up all your local route modules, and spits out a fully valid Postman v2.1 collection—grouped by URL segment and ready to import.

🚀 Key Benefits

• Instant Collection Generation
  Point the CLI at your entry file (app.js or app.ts) and get a complete Postman JSON in one command.

• Zero Boilerplate
  No decorators or special annotations—just your normal app.get() / router.use() calls.

• TypeScript-Ready
  Transpiles .ts on the fly, bundles your local modules, and externalizes your npm deps automatically.

• Organized Output
  Routes are grouped by their first path segment (/users, /comments, etc.), so your collection stays tidy.

• CLI & Programmatic
  Use it from the terminal or integrate generateCollection() into your build scripts, CI pipelines, or docs generator.

🎯 How It Works

1. Bundle Your App
   Under the hood, express-to-postman uses [esbuild] to bundle all local .js/.ts files into a single temporary ESM module. External npm packages (like express, cors, etc.) remain as imports.

2. Introspect Routes
   It dynamically imports that bundle, walks through the Express router stack, and extracts every route’s path and HTTP method—even those nested under sub-routers.

3. Emit Postman JSON
   It then constructs a v2.1 Postman Collection, grouping items by first path segment, and writes it to your chosen output file.

✨ Quick Start

# Install globally
npm install -g express-to-postman

# Generate a collection in one go
express-to-postman \
  -i ./src/app.ts \
  -o ./postman.collection.json

# Or as a dev dependency & npm script
npm install --save-dev express-to-postman

# package.json
"scripts": {
  "postman": "express-to-postman -i ./src/server.js -o ./collections/api.json"
}

📝 Example

Given this simple app.ts:

import express from 'express'
import userRouter from './routes/users'
export const app = express()

app.use('/users', userRouter)
app.get('/', (_req, res) => res.send('OK'))

Running:

express-to-postman -i src/app.ts -o postman.json

Produces a JSON with two folders—users and /—and three requests:

• GET /users
• POST /users/:id
• GET /

All ready for import into Postman or Newman.

🔧 Advanced Tips

• Verbose Mode: Add -v to see intermediate logs and the full JSON in your terminal.
• CI Integration: Run express-to-postman in your pipeline to always ship up-to-date API collections.
• Programmatic Use:

  import { generateCollection } from 'express-to-postman'
  await generateCollection('./dist/app.js', './api.postman.json', true)

🙌 Try It Today!

Stop spending hours maintaining Postman collections by hand. Install express-to-postman in seconds and let it keep your API docs in sync with your code.

npm install -g express-to-postman

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