what port range should I use for a local dev server?

Ports 1024-65535 avoid the privileged range reserved for standard services like HTTP or SSH. This is the tool's default, and it's a common convention for local development servers and ad hoc services.

does this check if the port is actually free on my machine?

No, it only generates a number within the range you set. It doesn't query your operating system or network, so confirm the port isn't already bound before using it.

can I generate multiple random ports without duplicates?

Yes, set Count to the number you need. The generator keeps drawing until it has that many distinct values, capped at however many ports actually exist in your chosen range.

what's the difference between well-known, registered and ephemeral ports?

Well-known ports, 0-1023, are reserved for standard services; registered ports, 1024-49151, are used by named applications; ephemeral ports, 49152-65535, are assigned temporarily by the OS. The tool's default range spans the latter two.

Random Port Generator

Pick random, unused-range TCP/UDP port numbers for local services, locally.

Local, Runs entirely in your browser, your data never leaves your device.

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Pick random port numbers within a range you set

This tool generates one or more random integers between a Min and Max you set, defaulting to 1024-65535, the non-privileged and ephemeral range, and deduplicates them so a batch never repeats a number, capped at however many ports actually exist in the range. It's useful for picking a port for a local dev server, a docker-compose mapping, or a config file, when you want a number unlikely to collide with a commonly used default. It does not check whether the port is actually free on your machine or network; it only generates a number.

How to use the Random Port Generator

Set Min and Max to the port range you want to draw from.
Set Count for how many distinct ports to generate at once.
Click Generate for a fresh batch, or reload the page for the default range.
Copy a single port, or use Copy all to grab the whole list.

The default range, 1024-65535, avoids the well-known ports below 1024 that are reserved for standard services. Numbers within a batch are always unique, but the tool has no way to check whether a given port is actually free on your machine or network.

Frequently asked questions

what port range should I use for a local dev server?: Ports 1024-65535 avoid the privileged range reserved for standard services like HTTP or SSH. This is the tool's default, and it's a common convention for local development servers and ad hoc services.
does this check if the port is actually free on my machine?: No, it only generates a number within the range you set. It doesn't query your operating system or network, so confirm the port isn't already bound before using it.
can I generate multiple random ports without duplicates?: Yes, set Count to the number you need. The generator keeps drawing until it has that many distinct values, capped at however many ports actually exist in your chosen range.
what's the difference between well-known, registered and ephemeral ports?: Well-known ports, 0-1023, are reserved for standard services; registered ports, 1024-49151, are used by named applications; ephemeral ports, 49152-65535, are assigned temporarily by the OS. The tool's default range spans the latter two.