IP Address Validator
Paste one address or five thousand. Each line is checked with a specific reason when it fails, rewritten in RFC 5952 canonical form, and classified against the IANA special-purpose registries — private, loopback, link-local, multicast, documentation, CGNAT and the rest.
About this tool
Use this when you need to check whether IP addresses are syntactically valid before they go into a firewall rule, allowlist, log pipeline, DNS zone or spreadsheet. Paste one address per line and the tool reports the canonical spelling, family, category and a specific reason for any bad line.
IPv4 and IPv6 are both supported. IPv6 output defaults to the RFC 5952 compressed form, so 2001:0DB8:0000:0000:0000:0000:0000:0001 becomes 2001:db8::1; switch to Expanded when you need all eight groups. Optional /prefix, :port, bracketed IPv6 authority syntax and %zone ids can be allowed or refused independently.
Classification is syntax-only and local: private, loopback, link-local, multicast, documentation, CGNAT/shared, unique-local, mapped IPv4, 6to4, Teredo, NAT64, benchmarking, broadcast, reserved and global addresses are labeled from their numeric ranges. Nothing is pinged, geolocated or sent over the network.
Choose Report for a readable audit, Table for CSV, JSON for automation, Valid only for a canonical list to paste elsewhere, Invalid only for cleanup, or Summary for totals by family/category. Drop duplicates compares canonical forms, so different IPv6 spellings of the same address collapse together.
Limits and edge cases:
- Up to 5,000 non-blank lines or 500,000 bytes per run.
- Leading-zero IPv4 octets are rejected by default because some legacy parsers treat them as octal; enable the checkbox only for decimal input you trust.
- Classification is based on address ranges, not reachability. A syntactically global address might still be blocked, unused or unrouted in the real network.
- Ports are validated as numbers in the range 0-65535 but the tool does not test whether anything is listening there.
FAQ
Does this check whether an address is reachable?
No. It validates syntax, canonicalizes the text and classifies the address range. It never pings, opens a socket, performs DNS, geolocates, or contacts a remote service.
Why are IPv4 leading zeros rejected?
They are ambiguous. Modern decimal-only parsers may read 192.168.001.010 as 192.168.1.10, while old C-derived parsers can interpret leading-zero octets as octal. The default rejects them; turn on Allow IPv4 leading zeros only when you know the source means decimal.
Can I validate CIDR prefixes and ports?
Yes. 10.0.0.0/8, 2001:db8::/32, 192.0.2.7:443 and [2001:db8::1]:443 are accepted by default and checked for family-specific prefix/port bounds. Disable the prefix or port checkbox when a field must contain a bare address.
What is the difference between compressed and expanded IPv6?
Compressed is the normal RFC 5952 style: lowercase hex, no leading zeroes, and the longest zero run collapsed to ::. Expanded writes all eight 16-bit groups with four hex digits each. Both identify the same address.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool ip-address-validate "192.168.1.1
2001:0DB8::1
100.64.0.1
10.0.0.0/8
[2001:db8::1]:443
192.168.1.256"New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/ip-address-validate/?addresses=192.168.1.1%0A2001%3A0DB8%3A%3A1%0A100.64.0.1%0A10.0.0.0%2F8%0A%5B2001%3Adb8%3A%3A1%5D%3A443%0A192.168.1.256&family=any&output=report&ipv6_form=compressed&allow_prefix=true&allow_port=true&allow_leading_zeros=true&dedupe=trueMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.