How to prepare Replit apps for production

Open the .replit file (enable Show hidden files in the file tree if needed). Add a [deployment] section with separate build and run commands. The build command runs once during deployment to compile your app. The run command starts your server in production. These are separate from the workspace run command, which only applies during development. Set deploymentTarget to cloudrun for Autoscale deployments.

1[deployment]
2build = ["npm", "run", "build"]
3run = ["node", "dist/index.js"]
4deploymentTarget = "cloudrun"

The most common deployment error is 'hostingpid1: an open port was not detected'. This happens because your server listens on localhost or 127.0.0.1, which is only accessible from within the container. Change your server to bind to 0.0.0.0 so it accepts connections from outside. Also ensure your port mapping is correct: your app should listen on a local port (like 3000) and .replit maps it to external port 80.

1// Express.js — correct production binding
2const express = require('express');
3const app = express();
4
5const PORT = process.env.PORT || 3000;
6const HOST = '0.0.0.0'; // Required for Replit deployments
7
8app.get('/', (req, res) => {
9  res.send('OK');
10});
11
12app.listen(PORT, HOST, () => {
13  console.log(`Server running on ${HOST}:${PORT}`);
14});

The [[ports]] section in .replit maps your application's local port to the external port that users access. External port must be 80 for web apps. If your app runs on port 3000 locally, configure the mapping so that external traffic on port 80 routes to your local port 3000. Without this mapping, the deployment health check cannot find your app and fails.

1[[ports]]
2localPort = 3000
3externalPort = 80

Workspace secrets do not automatically carry over to deployments. This is the number one cause of deployment failures. Open the Deployments pane in your Replit workspace, find the Secrets section, and add every environment variable your production app needs. This includes DATABASE_URL (auto-configured if using Replit's PostgreSQL), API keys, and any other credentials. Static deployments do not support secrets at all.

Replit's health check requests your homepage (/) after deployment. If it does not respond within 5 seconds, the deployment fails. Heavy initialization logic, slow database connections, or missing environment variables can all cause timeouts. Move expensive startup work to background tasks and make your root route respond immediately. For API servers without a homepage, add a simple health check endpoint at / that returns a 200 status.

1// Health check endpoint for API servers
2app.get('/', (req, res) => {
3  res.status(200).json({ status: 'healthy', timestamp: new Date().toISOString() });
4});
5
6// If your app has heavy initialization, do it after the server starts
7app.listen(PORT, HOST, () => {
8  console.log(`Server ready on ${HOST}:${PORT}`);
9  // Start heavy initialization after server is listening
10  initializeDatabase().catch(console.error);
11  warmCache().catch(console.error);
12});

Replit offers four deployment types. Autoscale scales to zero when idle (15-minute timeout) and charges per usage — best for web apps with variable traffic. Reserved VM stays always-on — best for WebSocket apps and background jobs. Static hosts HTML/CSS/JS only — free but no backend support. Scheduled runs on a cron schedule — best for periodic tasks. Click the Publish button, select your deployment type, configure CPU and RAM, and publish. For teams working on complex production deployments, RapidDev can help optimize architecture and deployment configuration.