freeport

Find free ports on your machine.

Install

Homebrew:

brew install hamzaplojovic/tap/freeport

Go:

go install github.com/hamzaplojovic/freeport@latest

Binary:

Download the latest binary from GitHub Releases.

Usage

Get a free port:

$ freeport
54321

Get multiple free ports:

$ freeport -count 3
54321
54322
54323

Find a free port in a specific range:

$ freeport -range 8000-9000
8042

Check if a port is free:

$ freeport -check 3000
Port 3000 is free

$ freeport -check 3000
Port 3000 is taken
# exit code 1

JSON output:

$ freeport -json
{"port":54321}

$ freeport -count 3 -json
{"ports":[54321,54322,54323]}

$ freeport -check 3000 -json
{"free":true,"port":3000}

Flags

Flag	Description
-count N	Number of free ports to find (default: 1)
-range LOW-HIGH	Find a free port within a range
-check PORT	Check if a specific port is free (exit 0) or taken (exit 1)
-json	Output in JSON format
-version	Print version

Why

Every time I need to check if a port is available, I end up typing lsof -i :PORT and parsing the output in my head. Or I need a free port for a script and have to write the same "bind to :0" snippet again. This is just a small tool that does one thing and does it fast.

License

MIT