Connect to a MongoDB database with Cloudflare Workers

Connect to a MongoDB database with Cloudflare Workers

Last updated Oct 16, 2026 In this tutorial, you will learn how to create a Cloudflare Workers application and connect it to a MongoDB database using the native Node.js driver. You will start with a direct connection from a Worker, then use a Durable Object to persist connections and reduce latency.

Note

Hyperdrive does not support MongoDB. Hyperdrive only supports PostgreSQL and MySQL wire protocols. To reduce connection latency with MongoDB, use a Durable Object as shown in this tutorial.

Prerequisites

To continue:

Sign up for a Cloudflare account ↗︎ if you have not already.
Install npm ↗︎.
Install Node.js ↗︎. Use a Node version manager like Volta ↗︎ or nvm ↗︎ to avoid permission issues and change Node.js versions.
Make sure you have access to a MongoDB database. You can use MongoDB Atlas ↗︎, a self-hosted MongoDB instance, or any other MongoDB-compatible host.

1. Create a Worker application

First, use the create-cloudflare CLI ↗︎ to create a new Worker application. To do this, open a terminal window and run the following command:

npmyarnpnpm

npm create cloudflare@latest -- mongodb-tutorial

yarn create cloudflare mongodb-tutorial

pnpm create cloudflare@latest mongodb-tutorial

This will prompt you to install the create-cloudflare ↗︎ package and lead you through a setup wizard.

For setup, select the following options:

For What would you like to start with?, choose Hello World example.
For Which template would you like to use?, choose Worker only.
For Which language do you want to use?, choose TypeScript.
For Do you want to use git for version control?, choose Yes.
For Do you want to add an AGENTS.md file to help AI coding tools understand Cloudflare APIs?, choose Yes.
For Do you want to deploy your application?, choose No (we will be making some changes before deploying).

If you choose to deploy, you will be asked to authenticate (if not logged in already), and your project will be deployed. If you deploy, you can still modify your Worker code and deploy again at the end of this tutorial.

Now, move into the newly created directory:

cd mongodb-tutorial

2. Enable Node.js compatibility

Node.js compatibility is required for the MongoDB driver, and needs to be configured for your Workers project.

For compatibility dates of 2026-08-04 or later, Workers and Pages projects enable both nodejs_compat and nodejs_compat_v2 by default. Built-in runtime APIs and polyfills are available without additional configuration. These flags are not used for these compatibility dates. Existing projects do not need to remove them when updating their compatibility date.

If your compatibility date is before 2026-08-04, add the nodejs_compat compatibility flag to your Wrangler configuration file to opt in:

{
    "compatibility_flags": [
        "nodejs_compat"
    ]
}

compatibility_flags = [ "nodejs_compat" ]

To turn off Node.js compatibility completely for a compatibility date of 2026-08-04 or later, remove the positive flags if present. Then add both no_nodejs_compat and no_nodejs_compat_v2. For configuration examples, refer to the Node.js compatibility flag.

3. Add the MongoDB connection library

To connect to a MongoDB database, you will need the mongodb library. In your Worker application directory, run the following command to install the library:

npmyarnpnpmbun

npm i mongodb

yarn add mongodb

pnpm add mongodb

bun add mongodb

Note

Make sure you are using mongodb version 6.15.0 or higher.

4. Configure the connection to the MongoDB database

Set your MongoDB connection string as a secret so that it is not stored as plain text. Use wrangler secret put with the example variable name MONGODB_URI:

npx wrangler secret put MONGODB_URI

Set your MONGODB_URI secret locally in a .env file as documented in Local Development with Secrets:

.envtoml

MONGODB_URI="<ENTER YOUR MONGODB CONNECTION STRING>"

5. Connect to the MongoDB database in the Worker

Open your Worker's main file (for example, src/index.ts) and import the MongoClient class from the mongodb library:

import { MongoClient } from "mongodb";

In the fetch event handler, create a new MongoClient instance and connect to the MongoDB database.

// create a new MongoClient instance using the connection string
const client = new MongoClient(env.MONGODB_URI);
// connect to the MongoDB database
await client.connect();

6. Interact with the movies database

To demonstrate how to interact with the movies database, you will fetch a document from the movies collection by querying the collection when a request is received.

Note

If you are following along with MongoDB Atlas, you can use the sample_mflix sample dataset. To load this data, open the Atlas console, navigate to your cluster, and select Load Sample Dataset.

Replace the existing code in your src/index.ts file with the following code:

src/index.jsjs

import { MongoClient } from "mongodb";

export default {
    async fetch(request, env, ctx) {
        const client = new MongoClient(env.MONGODB_URI);
        await client.connect();

        const movie = await client
            .db("sample_mflix")
            .collection("movies")
            .findOne(
                { title: "The Room" },
                { projection: { _id: 0, title: 1, imdb: 1 } },
            );

        return Response.json({ movie });
    },
};

src/index.tsts

import { MongoClient } from "mongodb";

export interface Env {
    MONGODB_URI: string;
}

export default {
    async fetch(request, env, ctx): Promise<Response> {
        const client = new MongoClient(env.MONGODB_URI);
        await client.connect();

        const movie = await client
            .db("sample_mflix")
            .collection("movies")
            .findOne(
                { title: "The Room" },
                { projection: { _id: 0, title: 1, imdb: 1 } },
            );

        return Response.json({ movie });
    },
} satisfies ExportedHandler<Env>;

This code establishes a connection to the MongoDB database within your Worker application and queries the movies collection, returning the result as a JSON response.

7. Deploy your Worker

Run the following command to deploy your Worker:

npx wrangler deploy

After deploying, you can interact with your MongoDB database using your Cloudflare Worker. Whenever a request is made to your Worker's URL, it will fetch data from the movies collection and return it as a JSON response.

8. Use a Durable Object to accelerate queries

Each Worker invocation creates a new TCP and TLS connection to MongoDB. For low-traffic use cases, this is acceptable. For latency-sensitive applications, place the MongoClient inside a Durable Object to persist the connection between requests.

Create a new file for the Durable Object class:

src/MongoDBConnection.jsjs

import { DurableObject } from "cloudflare:workers";
import { MongoClient } from "mongodb";

export class MongoDBConnection extends DurableObject {
    client;

    constructor(state, env) {
        super(state, env);
        this.client = new MongoClient(env.MONGODB_URI, {
            maxPoolSize: 1,
            minPoolSize: 0,
            serverSelectionTimeoutMS: 5000,
            maxIdleTimeMS: 20_000,
        });
    }

    async getMovie() {
        await this.client.connect();
        return this.client
            .db("sample_mflix")
            .collection("movies")
            .findOne(
                { title: "The Room" },
                { projection: { _id: 0, title: 1, imdb: 1 } },
            );
    }
}

src/MongoDBConnection.tsts

import { DurableObject } from "cloudflare:workers";
import { MongoClient } from "mongodb";

interface Env {
    MONGODB_URI: string;
}

export class MongoDBConnection extends DurableObject<Env> {
    private client: MongoClient;

    constructor(state: DurableObjectState, env: Env) {
        super(state, env);
        this.client = new MongoClient(env.MONGODB_URI, {
            maxPoolSize: 1,
            minPoolSize: 0,
            serverSelectionTimeoutMS: 5000,
            maxIdleTimeMS: 20_000,
        });
    }

    async getMovie() {
        await this.client.connect();
        return this.client
            .db("sample_mflix")
            .collection("movies")
            .findOne(
                { title: "The Room" },
                { projection: { _id: 0, title: 1, imdb: 1 } },
            );
    }
}

Update your Worker entry point to route requests to the Durable Object:

src/index.jsjs

import { MongoDBConnection } from "./MongoDBConnection";

export default {
    async fetch(request, env) {
        const id = env.MONGODB_CONNECTION.idFromName("mongodb-connection");
        const stub = env.MONGODB_CONNECTION.get(id, { locationHint: "enam" });
        const movie = await stub.getMovie();
        return Response.json({ movie });
    },
};

export { MongoDBConnection };

src/index.tsts

import { MongoDBConnection } from "./MongoDBConnection";

interface Env {
    MONGODB_URI: string;
    MONGODB_CONNECTION: DurableObjectNamespace<MongoDBConnection>;
}

export default {
    async fetch(request: Request, env: Env): Promise<Response> {
        const id = env.MONGODB_CONNECTION.idFromName("mongodb-connection");
        const stub = env.MONGODB_CONNECTION.get(id, { locationHint: "enam" });
        const movie = await stub.getMovie();
        return Response.json({ movie });
    },
} satisfies ExportedHandler<Env>;

export { MongoDBConnection };

Use the locationHint option to place the Durable Object close to your MongoDB cluster.

Configure the Durable Object binding and migration in your Wrangler file:

{
  "$schema": "./node_modules/wrangler/config-schema.json",
  "name": "mongodb-tutorial",
  "main": "src/index.ts",
  // Set this to today's date
  "compatibility_date": "2026-10-27",
  "compatibility_flags": [
    "nodejs_compat"
  ],
  "durable_objects": {
    "bindings": [
      {
        "name": "MONGODB_CONNECTION",
        "class_name": "MongoDBConnection"
      }
    ]
  },
  "migrations": [
    {
      "tag": "v1",
      "new_classes": [
        "MongoDBConnection"
      ]
    }
  ]
}

name = "mongodb-tutorial"
main = "src/index.ts"
# Set this to today's date
compatibility_date = "2026-10-27"
compatibility_flags = ["nodejs_compat"]

[[durable_objects.bindings]]
name = "MONGODB_CONNECTION"
class_name = "MongoDBConnection"

[[migrations]]
tag = "v1"
new_classes = ["MongoDBConnection"]

9. Redeploy your Worker

Run the following command to deploy your Worker:

npx wrangler deploy

Your Worker application is now live and accessible at <YOUR_WORKER>.<YOUR_SUBDOMAIN>.workers.dev, using a Durable Object to persist MongoDB connections. This reduces query latency from \~300 ms on cold requests to \~35 ms on warm requests.

Durable Object considerations

The connection is reused only while the Durable Object stays in memory. After a minute or two without requests, the Durable Object is evicted and its connection is dropped. The next request re-establishes the connection and pays the cold start cost again. This is expected behavior — there is no shutdown hook to close the connection manually, and none is needed.
Run all database logic inside the Durable Object. You cannot return MongoClient, Db, or Collection objects to the calling Worker over RPC.
A single Durable Object instance handles roughly 1,000 requests per second. To scale beyond this, distribute requests across multiple instances.

Next steps

To build more with databases and Workers, refer to Tutorials and explore the Databases documentation.

If you have any questions, need assistance, or would like to share your project, join the Cloudflare Developer community on Discord ↗︎ to connect with fellow developers and the Cloudflare team.

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description: This tutorial will guide you on how to build globally distributed applications with Cloudflare Workers, and Turso, an edge-hosted distributed database based on libSQL. title: Connect to and query your Turso database using Workers image: https://developers.cloudflare.com/workers/tutorials/connect-to-turso-using-workers/og.png?v=f2a414422c33aa66

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Connect to a MongoDB database with Cloud

Connect to a MongoDB database with Cloudflare Workers

Prerequisites

1. Create a Worker application

2. Enable Node.js compatibility

3. Add the MongoDB connection library

4. Configure the connection to the MongoDB database

5. Connect to the MongoDB database in the Worker

6. Interact with the movies database

7. Deploy your Worker

8. Use a Durable Object to accelerate queries

9. Redeploy your Worker

Next steps

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