Validate IPv4 octet ranges correctly instead of accepting anything shaped like four numbers.
Smart Regex Builder
Regex for IP Address Validation
Generate and test regex for IPv4 and IPv6 addresses in a browser-based regex builder that explains the pattern before you copy it.
Test real addresses and near-misses like 999.1.1.1 before you copy the IP regex.
- Save regex patterns, flags, and test strings in one browser workspace
- Resume validation work later with matching and failing examples intact
- Share the exact regex workspace when you want review or handoff
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Regex studio
Generate regex from examples
Generate a regex builder workflow from sample strings, explain regex clearly, and use the built-in regex tester in the same workspace.
Example strings
alex@example.com maya@company.io test.user@site.dev
/^[^\s@]+@[^\s@]+\.[^\s@]+$/i^Start of string
[^\s@]+One or more non-space characters before the @
@An @ symbol
\.[^\s@]+A dot and a domain segment
$End of string
Why it helps
Why generate IP address regex with a builder
Test valid addresses and invalid near-misses like 256.1.1.1 side by side.
Read a plain-English explanation of the octet groups so the rule stays maintainable.
How to use it
How to build an IP address regex
1 Paste addresses that should match, like 192.168.1.1 or 10.0.0.255.
2 Add out-of-range and malformed samples that should fail.
3 Review the generated pattern and explanation, then copy it into log filters or validation code.
Quick tips
IP address regex tips
A correct IPv4 octet is (25[0-5]|2[0-4]\d|1\d{2}|[1-9]?\d) — repeat it four times with dots; \d{1,3} alone accepts 999.
Full IPv6 regex is long due to :: compression — for validation, a parser or library is usually safer than a hand-rolled pattern.
For grep and log filtering, escape the dots: 192\.168\. — an unescaped dot matches any character.
FAQ
IP address regex questions
Can this generate regex for IPv4 addresses?
Yes. Add sample addresses and the builder generates a pattern you can test against valid addresses and out-of-range failures.
Why does \d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3} accept invalid IPs?
Because it allows any 1–3 digit number, including 999. Each octet needs an explicit 0–255 range group to reject out-of-range values.
Can regex validate IPv6 addresses?
Yes, but the pattern is long because of zero compression and mixed notation. For strict IPv6 validation, a parser is often the better tool.
Can I use the IP regex in grep or log searches?
Yes. Test the pattern against sample log lines first, and remember to escape dots so they match literally.
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