How to connect Replit to external databases

Open the Secrets tool from the Tools dock in the left sidebar. Add your database credentials as individual secrets or as a connection URI. Using individual secrets gives you more flexibility, while a connection URI is simpler for most libraries. Never hardcode credentials in your source code. Secrets are AES-256 encrypted and transmitted over TLS. Remember that collaborators with edit access can see secret values, so share workspace access carefully when database credentials are involved.

External databases typically restrict connections to known IP addresses. Since Replit runs on shared infrastructure, you may need to allow connections from all IPs (0.0.0.0/0) or use your database provider's specific configuration for cloud-hosted clients. Check your database provider's documentation for firewall or allowlist settings. On services like Supabase, PlanetScale, and MongoDB Atlas, there is usually an IP allowlist section in the dashboard where you can add 0.0.0.0/0 for development or configure more restrictive rules for production.

Install the pg package for Node.js or psycopg2 for Python from the Shell. Use the connection string stored in your Secrets to establish a connection. For SSL connections, which most cloud-hosted PostgreSQL providers require, set the ssl option to reject unauthorized certificates or provide a CA certificate. Test the connection by running a simple query like SELECT NOW() to confirm it works.

1// Node.js — PostgreSQL connection
2import pg from 'pg';
3const { Pool } = pg;
4
5const pool = new Pool({
6  connectionString: process.env.DATABASE_URL,
7  ssl: {
8    rejectUnauthorized: false // Set to true with CA cert in production
9  }
10});
11
12async function testConnection() {
13  try {
14    const result = await pool.query('SELECT NOW()');
15    console.log('Connected:', result.rows[0].now);
16  } catch (error) {
17    console.error('Connection failed:', error.message);
18  }
19}
20
21testConnection();

Install the mysql2 package for Node.js or mysql-connector-python for Python. MySQL connections follow a similar pattern: read credentials from environment variables and establish a pool or single connection. Most cloud MySQL providers like PlanetScale require SSL. The mysql2 package supports SSL natively through the connection configuration.

1// Node.js — MySQL connection
2import mysql from 'mysql2/promise';
3
4const pool = mysql.createPool({
5  host: process.env.DB_HOST,
6  port: parseInt(process.env.DB_PORT || '3306'),
7  user: process.env.DB_USER,
8  password: process.env.DB_PASSWORD,
9  database: process.env.DB_NAME,
10  ssl: {
11    rejectUnauthorized: true
12  }
13});
14
15async function testConnection() {
16  try {
17    const [rows] = await pool.query('SELECT NOW() as now');
18    console.log('Connected:', rows[0].now);
19  } catch (error) {
20    console.error('Connection failed:', error.message);
21  }
22}
23
24testConnection();

Install the mongodb package for Node.js or pymongo for Python. MongoDB Atlas provides a connection URI that includes the cluster address, credentials, and database name. Store the full URI in Secrets as MONGODB_URI. MongoDB Atlas connections use TLS by default, so no additional SSL configuration is needed in most cases.

1// Node.js — MongoDB connection
2import { MongoClient } from 'mongodb';
3
4const uri = process.env.MONGODB_URI;
5const client = new MongoClient(uri);
6
7async function testConnection() {
8  try {
9    await client.connect();
10    const db = client.db('myapp');
11    const result = await db.command({ ping: 1 });
12    console.log('Connected to MongoDB:', result);
13  } catch (error) {
14    console.error('Connection failed:', error.message);
15  } finally {
16    await client.close();
17  }
18}
19
20testConnection();

This is the step most developers forget. Workspace secrets do not carry over to deployments. Open the Deployments pane from the left sidebar, find the Secrets section, and add every database credential your app needs. Use production database credentials here, which may differ from development values. If you skip this step, your deployed app will crash with errors about undefined connection strings or failed authentication.