Describe what you want to match in plain English, paste a few example strings, and get a regex — then watch it actually run against your examples right here, with every match highlighted. Free, no sign-up, nothing stored on our side.
How it works
- Describe it. Say what should match and what should not, in plain English. “ISO dates like 2026-09-30 but not 30/09/2026” is enough to start.
- Give it real examples. Paste the actual strings you are working with, including the ones that must not match. The examples are what turn a plausible pattern into a correct one.
- Run it. The pattern is compiled in your browser and executed against every sample you gave, line by line, with the matched part highlighted. No waiting, no server round trip — the test happens locally the moment the answer arrives.
Why generate and test in the same place
Most AI regex tools stop at the string. You get a pattern that looks right, paste it into your editor, and find out it is wrong three edge cases later. The review round is on you.
This page closes that loop. Because the test runs in your browser the instant the pattern is generated, you find out in seconds whether it behaves the way you described — including the strings you deliberately included to break it. If a sample does not match, you can change the description and try again without leaving the page.
Every result is saved in your browser, so you can come back to it, and you can download everything as JSON.
What it is good for
- Validating form input — emails, phone numbers, order IDs, dates
- Parsing logs and extracting fields
- Writing the pattern for a find-and-replace you are about to run on real data
- Understanding a pattern someone else wrote
Honest limitations
- The live test executes JavaScript flavour. If you pick Python, PCRE, Go or Java, the pattern and explanation are still written for that flavour, but the in-page execution is JavaScript. For most patterns that is the same result; for the handful that differ (lookbehind support, named group syntax, unicode classes) treat the test as indicative and verify in your own runtime.
- It does not prove a pattern is exhaustive. A passing sample set is not a proof. Include your nastiest real cases — that is what the test is for.
- It will tell you when regex is the wrong tool. For nested structures like HTML or JSON, a parser beats a pattern, and the tool says so rather than handing you something fragile.
FAQ
Is it free?
Yes, and there is no account. You do not need an email to generate or to test.
Where are my patterns stored?
In your own browser, on your own device. Your input is sent to the model for that one generation and is not saved on our side. You can clear or export your saved results at any time from the bottom of the tool.
Which flavours are supported?
JavaScript, Python, PCRE/PHP, Go, Java and Ruby. JavaScript is the one that is executed live in the page.
Can it explain a pattern I already have?
Yes. Put the pattern in the description field and say you want it explained, and add a few sample strings — the breakdown comes back token by token, and your samples still get run against it.
What if the pattern is wrong?
That is what the sample test is for. If a string you expected to match shows “no match”, say so in the description and run it again — iterating on real failing examples is far faster than reading a pattern and hoping.