Development and production databases

​

How they compare

​

Create a production database when you publish

• Current infrastructure (Helium): Replit automatically creates a production database when you publish, provided your development database contains data.
• Legacy Neon development databases: You create the production database from the publish settings. Open Database settings while publishing, turn on Create production database, and optionally turn on Set up your production database with your current development data to copy your development data across.

​

Find which database your app uses

• Project Editor: In your workspace, the Shell, and Agent’s sessions, DATABASE_URL points to the development database. Replit connects it automatically, so on current infrastructure it doesn’t appear in Secrets.
• Published app: When you publish, your app gets a separate DATABASE_URL that points to the production database.

​

Ask Agent to check

Check which database my app uses, without showing any secret values or changing anything:
1. Find the environment variable my code reads to connect to its database (for example DATABASE_URL) and show me the file and line.
2. Check whether my Secrets include a DATABASE_URL I added myself or any other database connection, and list only the names.
3. Run a read-only query on my production database: list its tables and show the five newest rows in my main table, so I can compare them with my live app.

​

Check in the Database tool and Publishing

1

Open your production database

In the Database tool, open the database menu next to All Databases and select Production.

2

Find a record from your live app

Open My Data and look for something you recently created in your published app, such as a new account or order. If you can see it, your published app writes to this database. Production opens in read-only mode, so browsing it is safe.

3

Compare the connection settings

Open the production database’s Settings tab and find Connection string. Then open Publishing, select Adjust settings, and find DATABASE_URL under Production app secrets. Reveal each value and check that both point to the same host. For most apps, that means the same endpoint ID, the part that starts with ep-. A pooled address adds -pooler after the ID, so the full strings don’t have to match exactly.

Both values include your database password. Compare them yourself; don’t paste them into a chat, support ticket, or screenshot.

4

Check Secrets for another database

Open Secrets. Replit’s built-in connection isn’t listed there. If you see a DATABASE_URL you added yourself, or another database connection such as SUPABASE_DATABASE_URL, your app may use that database instead. Ask Agent which one your code reads. A NEON_DATABASE_URL secret is your previous development database connection, saved during the database infrastructure upgrade. Your app only uses it if your code reads it.

​

What the results mean

​

Connection pooling

​

Making safe changes to your production database

• Removing columns or tables that still contain data
• Changing column data types, which can fail if existing values don’t convert
• Adding required fields without default values to tables that already have rows
• Renaming tables or columns: confirm the rename when Publish asks, or the data is dropped
• Adding unique constraints to tables whose existing rows may violate them

​

Test changes with a publish preview

• Verify your app still works with the database changes applied, across your major user flows
• Confirm existing data was properly migrated and new fields contain expected values
• Watch for performance regressions in query response times

​

Billing and resource usage

​

Removing a production database

​

Legacy development database

​

Database infrastructure upgrade

• Lower latency and more storage: Your database runs on Replit infrastructure alongside your app, and your storage limit increases from 10 GB to 20 GB, or to 50 GB on Pro and Enterprise plans.
• Same database engine: Helium uses PostgreSQL 16, the same version as Neon. Your queries, schemas, and data work the same way.
• Connection updates automatically: DATABASE_URL is updated to point to Helium. Your previous Neon connection string is saved as NEON_DATABASE_URL in your Secrets for reference.
• Individual PG variables removed: PGHOST, PGPORT, PGUSER, and PGPASSWORD are removed. Use DATABASE_URL instead.

• Hardcoded Neon connection strings: Update code that references a neon.tech connection string to use the DATABASE_URL environment variable instead.
• Custom PostgreSQL roles: Roles and permissions migrate automatically, but role passwords can’t be copied. Reset passwords for custom roles on the new database.

​

SSL connection errors after the upgrade

// Before (breaks after upgrade)
const pool = new Pool({
  connectionString: process.env.DATABASE_URL,
  ssl: { rejectUnauthorized: false },
});

// After (works in both development and production)
const pool = new Pool({
  connectionString: process.env.DATABASE_URL,
  ssl:
    process.env.NODE_ENV === "production"
      ? { rejectUnauthorized: false }
      : false,
});

​

Forked apps that shared a database

​

Next steps

• How Publish updates your production database: Review, test, and approve schema changes when you publish.
• Data recovery: Restore development or production data.
• Connection details: Find your database’s connection string.
• Work with your data: Browse, edit, and query your data.