BYTETOOLS

IP Address Validator

Validate lists of IPv4, IPv6 and CIDR entries with the exact failure reason per line — compressed ::, IPv4-mapped forms and prefixes included. Free.

6
Lines checked
4
Valid
2
Invalid

Validation results

InputTypeDetail
192.168.1.1IPv4valid IPv4 address
192.168.1.256invalidoctet 4 (256) is greater than 255
2001:db8::1IPv6valid IPv6 address
::ffff:10.0.0.1IPv6valid IPv6 (IPv4-mapped ::ffff: form)
10.0.0.0/8IPv4 CIDRvalid IPv4 network, prefix /8
fe80::1::2invalidmore than one "::" — an IPv6 address may compress zeros only once

What is the IP Address Validator?

The IP Address Validator checks a whole list of addresses at once and tells you, line by line, whether each one is valid IPv4, valid IPv6, valid CIDR — or invalid, with the precise reason: an octet above 255, five dotted parts, a double "::", a hex group that is too long, or a prefix out of range.

  • Validates IPv4, IPv6 and CIDR notation in one mixed list
  • Exact per-line failure reasons, not just a red cross
  • Full IPv6 support: :: compression and IPv4-mapped addresses
  • Warns about leading-zero octets that parsers may treat as octal
  • Family-aware prefix bounds: /0–32 for IPv4, /0–128 for IPv6
  • Copy only the valid lines with one click

How to use the IP Address Validator

  1. 1

    Paste your addresses into the input, one per line — IPv4, IPv6 and CIDR can be mixed.

  2. 2

    Read the verdict for each line: its detected type or the exact reason it failed.

  3. 3

    Check the valid/invalid summary counts.

  4. 4

    Click Copy valid lines to export only the entries that passed.

About the IP Address Validator

The IP Address Validator checks a whole list of addresses at once and tells you, line by line, whether each one is valid IPv4, valid IPv6, valid CIDR — or invalid, with the precise reason: an octet above 255, five dotted parts, a double "::", a hex group that is too long, or a prefix out of range.

It understands the full IPv6 syntax including :: zero compression and IPv4-mapped addresses like ::ffff:10.0.0.1, and validates CIDR prefixes against the right bounds for each family (0–32 for IPv4, 0–128 for IPv6). It even flags valid-but-risky forms such as IPv4 octets with leading zeros, which some parsers silently read as octal.

Paste config files, log extracts or spreadsheet columns — validation runs instantly and entirely in your browser, and the one-click copy exports just the valid lines for reuse.

Frequently asked questions

What makes an IPv4 address valid?

Exactly four decimal numbers from 0 to 255 separated by dots, nothing more. 192.168.1.256 fails because 256 exceeds 255, and 192.168.1 fails because it has only three octets — the validator names the exact octet at fault.

How is an IPv6 address validated?

It must reduce to eight 16-bit hex groups. The "::" shorthand may appear once and expands to enough zero groups to reach eight, each group holds one to four hex digits, and an IPv4 dotted tail like ::ffff:10.0.0.1 counts as the last two groups.

Why is an address with two "::" invalid?

Because the expansion would be ambiguous — there would be no way to know how many zero groups each "::" stands for. RFC 4291 therefore allows the compression exactly once per address, and the validator flags a second occurrence explicitly.

Are leading zeros allowed in IPv4 octets?

They parse, but they are dangerous: many libraries (inet_aton, some URL parsers) treat 010 as octal 8, not decimal 10. The validator accepts the address but adds a warning so you can normalize it before it bites.

Does the validator check whether the IP actually exists or responds?

No — it checks syntax and ranges only, entirely offline in your browser. Whether an address is reachable, assigned or routable is a network question this tool deliberately does not (and cannot) answer without sending packets.

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