This tool will take a list of IP addresses and/or prefixes, and aggregate them to the minimum exactly equivalent list of prefixes. It will minimize the list but not change the substance of it.

Notes:

• The only accepted format for IPv4 addresses is a dotted-quad with no leading zeros. IPv6 addresses are accepted in any valid string representation.
• A following prefix length, separated by / is optional. If omitted a single host address is assumed.
• IPv4 prefix length may be specified as an integer number of bits in the mask (eg. 1.1.1.0/24), as a netmask (eg. 1.1.1.0/255.255.255.0), or as a wildcard mask (eg. 1.1.1.0/0.0.0.255). Discontiguous masks are not accepted. All examples are equivalent.
• IPv6 prefix length must be an integer number of bits in the mask (eg. 2001:db8::/32).
• Prefix addresses with host-bits set are invalid but accepted for convenience. Host bits will be cleared in the output. For example 1.2.3.4/24 will be presented in the output as 1.2.3.0/24.
• Output will always be in canonical CIDR form, like 1.1.1.0/24 or 2001:db8::1:0:0/96 (RFC5952). Prefix length is always included for host addresses.
• IPv4-mapped IPv6 prefixes (ie. ::ffff:0:0/96) are treated as IPv6, distinct from IPv4 prefixes, and not aggregated together with them.

Mirrors:

This tool is available at several locations:

• Primary https://ip-aggregator.nonexistent.ca
• Fly.io https://ip-aggregator.fly.dev

Contact:

Questions? Comments? Suggestions? Message (don't chat) me at /u/error404 or error404·nonexistent·ca.