Random port generator
Generates a random port number above 1024, for starting local services or writing tests.
Generate random port numbers outside of the range of "known" ports (0-1023).
Steps and notes
What is Random port generator?
Pick a random TCP/UDP port number in the range 1024 to 65535, inclusive — the unprivileged space, deliberately excluding the well-known 0-1023 range that on Unix-like systems requires root to bind. Useful when a local dev server, a test harness, a proxy config or a demo needs a port that will not collide with SSH, HTTP or DNS, and when you want a number you can paste rather than one you have to invent. Refresh for a new value; nothing is checked against your machine, because the tool cannot see it.
- Click generate to get a port
- Copy and use it
- Generate again if you need several
- The range is 1024-65535 inclusive, so 1024 and 65535 can both come back.
- It does not check availability: a random port is unlikely to be in use, but “unlikely” is not “free” — bind and handle the error, or use port 0 to let the OS choose.
- Registered service ports above 1024 (3306 MySQL, 5432 PostgreSQL, 6379 Redis, and so on) are inside the range and can be returned.
Frequently asked questions
- Why exclude ports 0–1023?
- The well-known range is reserved for system services (SSH 22, HTTP 80…) and binding to it usually requires administrator rights. Random picks there would mostly fail or shadow real services.
- Does a random port guarantee it is free?
- No — nothing else on your machine claimed it at generation time, but you should still check with netstat or your runtime before binding. The tool gives you a sane candidate, not a reservation.
- Which range do the numbers come from?
- The registered/ephemeral range above 1023 (up to 65535). For services exposed to others, the conventional registered range is 1024–49151.
- Should I just bind port 0 instead?
- When the port genuinely has to be available, yes: binding port 0 asks the kernel to allocate an unused one and you read the number back from the socket. Use this generator when you want a plausible, stable-looking number to paste into a config file or a screenshot, and port 0 when correctness at bind time is what matters.
- Why is my database port a possible answer?
- Because 1024-65535 contains both ephemeral/client space and the registered service ports that modern databases live on. If you need a port that will not be mistaken for a service, narrow the search yourself (for example 20000-29999) and re-roll until it lands where you want.
Category: Development