IP list sorter & deduplicator

Frequently asked

Why does sort put 10.0.0.10 before 10.0.0.9?

Because a plain text sort compares character by character, and '1' sorts before '9'. Addresses only sort correctly as text when every octet is zero-padded to three digits. This tool sorts on the 32-bit numeric value instead, which is what you almost always mean.

How do I sort IPs correctly on the command line?

sort -t . -k1,1n -k2,2n -k3,3n -k4,4n treats each octet as its own numeric key and gives the right order. The -V flag (version sort) usually works too and is shorter to type, though it is comparing version strings rather than addresses, so it will do something surprising if the list contains anything that is not an address.

What happens to ports and CIDR blocks?

A trailing :port is stripped when what remains is a valid address, so 198.51.100.22:8443 becomes 198.51.100.22. CIDR blocks are not expanded — a token like 10.0.0.0/24 is reported as unrecognised rather than silently turned into one address or 256 of them. Use the IP range generator if you want a block expanded.

Does anything I paste get sent to you?

No. The parsing and sorting run entirely in your browser — the page makes no request while you use it. That is worth knowing given the lists people paste into tools like this usually come from access logs.