---
name: mongodb-express
description: "Provisions a MongoDB database for a Express app with `npx extraorbital add mongodb` (no signup, no card) and wires it into Express with `mongodb`. Use when a Express project needs MongoDB, Mongo, a document database, MONGODB_URI or Mongoose, or when MONGODB_URI is missing or unset in .env."
---

# MongoDB in Express

<!-- Generated from ExtraOrbital's service registry by `pnpm skills:build` in platform/app. Edit the generator, not this file. -->

ExtraOrbital provisions a MongoDB database in one command and writes the credentials into the project's env file. For anything this recipe does not cover, use the `extraorbital` skill or https://extraorbital.dev/llms.txt.

## 1. Provision

```bash
npx extraorbital add mongodb
```

Run it from the project root. It is idempotent (a second run returns the same resource) and writes to `.env.local` if the project has one, otherwise `.env`, keeping that file out of git. Add `--json` to parse the result; credential values are redacted there, and you should never print them either.

| Variable | |
| --- | --- |
| `MONGODB_URI` | Carries the user, the password, TLS and the one database they reach |

Free on the Prototype plan: 512 MB, shared RAM and vCPU.

## 2. Install the client

```bash
npm install mongodb
```

## 3. Connect

Node does not read env files by itself: start with `node --env-file=.env` (Node 20.6+), naming `.env.local` instead if that is where ExtraOrbital wrote, or load it with `dotenv`.

**`src/mongodb.js`**

```js
import { MongoClient } from "mongodb";

export const mongo = new MongoClient(process.env.MONGODB_URI);
// The database named in the connection string: the only one the credentials reach.
export const mongoDb = mongo.db();
```

## 4. Use it

**`src/app.js`**

```js
import { mongoDb } from "./mongodb.js";

// Express 5 sends a rejected promise to the error handler; on Express 4, wrap this in try/catch.
app.get("/api/mongodb", async (req, res) => {
  await mongoDb.collection("events").insertOne({ type: "ping", at: new Date() });
  const events = await mongoDb.collection("events").countDocuments();
  res.json({ events });
});
```

## 5. Verify

```bash
npx extraorbital list        # the resource is listed as active
node --env-file=.env src/server.js
curl http://localhost:3000/api/mongodb
```

A JSON answer means the credentials, the client and the route all work. Delete the route afterwards if the app does not need it.

## Pitfalls

- Call `db()` with no name: the user in `MONGODB_URI` is scoped to the database in the string.
- Create the client once, as here; the driver pools connections and connects lazily on the first command. With Mongoose, `mongoose.connect(MONGODB_URI)` takes the same string.
- Snippets are ES modules (`"type": "module"`). In CommonJS, swap `import` for `require`.
- Create clients once at module scope, as here, not per request.
- Exit code 3 means the account is past its free allowance: show the human the link the command printed and wait. Do not retry or work around it.

Docs: https://extraorbital.dev/docs/resources/mongo.md