Regex Tester
Test regex with live match highlighting.
100% private — runs in your browser, nothing is uploaded.
| # | Match | Index | Groups |
|---|---|---|---|
| 1 | alice@example.com | 8 | — |
| 2 | bob@test.org | 29 | — |
| 3 | carol@old.net | 68 | — |
How to use the Regex Tester
- 1Enter your pattern
Type the regular expression you want to test.
- 2Choose flags
Toggle g, i, m or s to change how matching behaves.
- 3Paste your text
Add the text you want to search.
- 4Read the matches
Matches are highlighted, with positions and capture groups listed.
Examples
| Input | Output |
|---|---|
\d+ on 'abc 123 xyz 45' | matches: 123, 45 |
\b\w+@\w+\.\w+\b | matches email-like strings |
Free online regex tester
This regex tester lets you build and debug a regular expression against real text, with every match highlighted live as you type. Capture groups, match positions and the standard flags are all shown, so you can see exactly what your pattern is doing.
A quick regex cheat sheet
\d— any digit ·\w— word character ·\s— whitespace.— any character (except newline, unless thesflag is set)*— zero or more ·+— one or more ·?— optional{2,5}— between 2 and 5 times^— start ·$— end ·\b— word boundary[abc]— any one of these ·(...)— capture group ·|— or
The most common mistake
Forgetting to escape special characters. A dot means “any character,” so example.com also matches exampleXcom. To match a literal dot, escape it: example\.com. The same applies to ? + * ( ) [ ] { } ^ $ | and the backslash itself.
Everything runs in your browser, so your patterns and test data stay private and the tool works offline.
Frequently Asked Questions
How do I test a regular expression?
Type your pattern in the regex field and paste your text below it. Every match is highlighted instantly, with a table showing each match, its position and any capture groups.
What do the g, i, m and s flags mean?
g finds all matches instead of just the first. i makes matching case-insensitive. m makes ^ and $ match the start and end of each line. s lets the dot match newline characters.
What are capture groups?
Parentheses in a pattern create capture groups, which extract part of a match. For example (\d{4})-(\d{2}) captures a year and a month separately. The groups appear in the results table.
Which regex flavour does this use?
JavaScript (ECMAScript) regular expressions, since it runs in your browser. This is very close to PCRE, though a few advanced constructs differ.
Why does my pattern match nothing?
Common causes are forgetting to escape special characters like . or ?, missing the i flag when case differs, or the dot not matching newlines without the s flag.
Is my text private?
Yes. The regex runs entirely in your browser, so your pattern and test data are never uploaded and the tool works offline.