Regex tester
Test regular expressions with live highlights
Runs in your browser. Nothing is uploaded.
How it works
A regular expression is a short pattern that finds text. Enter a pattern and some test text to see every match highlighted, with its position and groups in a table. Patterns run in the background with a one-second limit, so one that would run for ever can’t freeze your browser. Nothing is uploaded.
Your pattern runs against your text, and every match is highlighted.
This uses the JavaScript regex engine, the same one your browser runs. Flags change how a pattern behaves, such as ignoring case.
Some patterns get exponentially slower on certain text. We stop those after a second, and tell you why.
Worked example. The pattern \d+ means “one or more digits”, so in “a1 b22” it finds 1 and 22.
Examples
| Pattern | Finds |
|---|---|
| \d+ | Numbers |
| ^\w+ | The first word |
| \s+ | Spaces |
| [aeiou] | Vowels |
What this tool doesn’t cover
- Other languages have slightly different regex rules.
- We show up to 1,000 matches.
Questions
Why did my pattern time out?
It may backtrack too much, often from nested repeats such as (a+)+. Try a simpler pattern.
Which regex flavour is this?
JavaScript, as used in browsers and Node.js.
Is my text uploaded?
No. Everything runs in your browser.
How do I test a regular expression?
Enter a pattern and some sample text. Matches are marked as you type, so you can adjust it until it’s right.
What do the g and i flags do?
The g flag finds every match, not just the first. The i flag ignores upper and lower case.
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