next start

Start a production Next.js server after building with next build.

next start starts the application in production mode. The application must be compiled first with next build.

next start [directory] [options]

Options

[directory] · string

The directory containing the Next.js application. Defaults to the current working directory.

-p / --port <port> · number · default: "3000"

Port number to listen on. Can also be set via the PORT environment variable.

-H / --hostname <hostname> · string · default: "0.0.0.0"

Hostname to bind the server to.

--keepAliveTimeout <milliseconds> · number

Maximum time in milliseconds to wait before closing inactive keep-alive connections. Important when deploying behind a load balancer.

--experimental-cpu-prof · boolean

Enable CPU profiling via V8’s inspector. Profiles are saved to .next/cpu-profiles/ on process exit.

-h / --help · boolean

Show all available options.

Environment variables at start time

Environment variables loaded by next start depend on where they are defined:

Source	When loaded	Notes
.env	Build time	Values baked into the bundle
.env.local	Build time	Local overrides, not committed
.env.production	Build time	Production-only values
System environment	Runtime	Set in your deployment platform or shell

NEXT_PUBLIC_* variables are inlined at build time and cannot be changed at start time. Server-only variables (without the NEXT_PUBLIC_ prefix) can be changed between builds if you read them at request time.

PORT cannot be set in .env files. The HTTP server starts before environment files are loaded. Pass PORT as a system environment variable or use the -p flag.

Examples

Start on a custom port

next start -p 8080
# or
PORT=8080 next start

Bind to a specific hostname

next start --hostname 127.0.0.1

Configure keep-alive timeout for a load balancer

When deploying behind a load balancer (e.g. AWS ELB/ALB), set the keep-alive timeout to a value greater than the load balancer’s idle timeout to prevent connection termination errors:

next start --keepAliveTimeout 70000

CPU profiling

next start --experimental-cpu-prof

Profiles are saved as start-main-*.cpuprofile in .next/cpu-profiles/. Open them in Chrome DevTools under the Performance tab.

Serving a standalone build

If you built with output: 'standalone', use the generated minimal server instead of next start:

# Copy static assets first
cp -r public .next/standalone/ && cp -r .next/static .next/standalone/.next/

# Start the standalone server
node .next/standalone/server.js

The standalone server reads PORT and HOSTNAME environment variables:

PORT=8080 HOSTNAME=0.0.0.0 node .next/standalone/server.js

Version history

Version	Changes
v15.0.0	Turbopack stable for dev; next start unchanged
v13.0.0	App Router support added