AI Regex Builder

Reading your input…

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About this tool

Describe what to match and get the pattern, a breakdown of every part, and what it deliberately misses.

A regex you cannot read is a regex you cannot maintain, and copying one off the internet means owning a pattern you do not understand until the day it silently fails on an edge case.

Describe what should match, in your own words, and get the pattern with a breakdown of each component, plus an explicit statement of what it does not match. Include some inputs that should fail — those are what expose a sloppy pattern. It warns about catastrophic backtracking where nested quantifiers could hang on a long input, which is a real denial-of-service vector and not a theoretical one. It will also tell you when a regex is simply the wrong tool: parsing HTML or fully validating email addresses being the two classic cases where the correct answer is a parser or a confirmation link.

How to use

  1. Describe what the pattern should match, add sample inputs including some that should NOT match, and pick your regex flavour
  2. Press Generate and give it a few seconds.
  3. Copy what you need, or generate again for a different take — every run is fresh.

Frequently asked questions

Lookbehind, named groups and Unicode property escapes differ across engines. A pattern that works in PCRE can throw a syntax error in JavaScript, so the flavour is applied when building it.

Nested quantifiers can make an engine try exponentially many combinations on a long non-matching input, hanging the process. It is a genuine DoS vector, so risky patterns are flagged.

Generally no. The full specification is far more permissive than most patterns allow, so strict regexes reject valid addresses. Check for an @ with something either side, then send a confirmation email.

No. Your input is sent to the AI provider this site is configured to use purely to generate your result, and is not stored here afterwards. There is no account for it to be attached to. Even so, keep passwords, financial details and other people's private information out of it.

The site owner selects one model that powers every tool here, so there is nothing for you to configure. Describe what you need, press Generate, and read the result before you use it.