IP / CIDR Validator - IPv4, IPv6 & Prefix Length
Validate IPv4, IPv6, and CIDR notation with numeric checks and clear errors. Local, privacy‑friendly validation.
Keywords
IP validator, IPv4 validator, IPv6 validator, CIDR validator, network prefix, subnet
IP addresses and CIDR notation identify hosts and networks. This page validates IPv4, IPv6, and prefix lengths with numeric checks to catch common mistakes.
What is CIDR?
Classless Inter‑Domain Routing expresses a network as an address plus a prefix length—/24 for IPv4 or /64 for IPv6. The prefix indicates how many leading bits form the network portion.
How validation works
IPv4 segments must be 0–255 without leading zeroes. IPv6 supports eight hex groups with optional :: compression. For CIDR, the prefix length must be within 0–32 (IPv4) or 0–128 (IPv6).
About this validator
The goal is correctness with clear feedback, not full subnet math. For network planning, pair this with tools that compute ranges, masks, and broadcast addresses.
FAQ
Does this compute network ranges?
No. It verifies syntax and prefix bounds. Use a subnet calculator for ranges and masks.
Why is 01.2.3.4 invalid?
IPv4 segments must not contain leading zeroes to avoid octal ambiguity.
Accurate input prevents routing and security errors. Validate early and use authoritative libraries in back‑end services.