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IPv4 Address Validator

Paste one or many IPv4 addresses to see whether each is valid, why not if it is not, and what kind of address it is.

Processed locally in your browser

0 chars · 0 lines
The result will appear here.

What is IPv4 Address Validator?

A valid IPv4 address is four decimal octets from 0 to 255 separated by dots. Many parsers are lenient and accept forms such as 010.0.0.1 (octal) or 1.2.3 (shorthand), which is a well-known source of security bugs, so this validator is deliberately strict and explains the exact reason for every rejection.

For valid addresses it reports the classful class (A–E) and classifies the address against the special-purpose registries: private RFC 1918, loopback, link-local (APIPA), CGNAT shared space, documentation TEST-NET, benchmarking, multicast, reserved and broadcast. Binary, decimal and hex forms are shown for single addresses.

How does it work?

  1. Paste one address per line (or a single address).
  2. For a single address you get a details panel; for several you get a table with class, type or the reason for failure.
  3. Look at the status banner for the count of invalid lines.
  4. Fix reported issues such as leading zeros or octets above 255 and re-check.

Common use cases

  • Validating an exported list of addresses before importing it into a firewall or database.
  • Checking whether an address is private or publicly routable before opening a port.
  • Spotting typos like 192.168.1.256 or 192.168..1 in configuration files.
  • Teaching or learning special-purpose ranges such as 100.64.0.0/10 and 169.254.0.0/16.

Examples

Try this input in the tool above:

Input
192.168.1.10
8.8.8.8
256.1.1.1
010.0.0.1
Output
Address | Valid | Class | Type / reason
192.168.1.10 | Yes | C | Private (RFC 1918)
8.8.8.8 | Yes | A | Public (globally routable)
256.1.1.1 | No | — | Octet out of range (must be 0-255) (256)
010.0.0.1 | No | — | Leading zeros are not allowed (ambiguous: some systems read them as octal) (010)

Privacy

IPv4 Address Validator runs entirely in your browser. The text or files you provide are processed on your device and are not uploaded, logged or stored on our servers.

Limitations

Validation is purely syntactic and range-based: it cannot tell whether an address is reachable, assigned or in use, and no lookup or ping is made.

Frequently asked questions

Why is 192.168.01.1 rejected?

Leading zeros are ambiguous: some libraries read 01 as decimal and others as octal. Strict validators reject them; remove the zero.

What is 100.64.0.0/10?

It is the shared address space reserved for carrier-grade NAT (RFC 6598). It is neither RFC 1918 private nor public internet space.

Does "valid" mean the host exists?

No. It only means the text is a well-formed IPv4 address. Nothing is contacted.

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