Regex Tester

Highlight regular expression matches as you type, list every match and capture group, and start from common patterns

Runs locally in your browser. Nothing is uploaded.

Regular expression

Flags

g globalFind every match, not just the firsti ignore caseTreat A and a as the same letterm multiline^ and $ match at the start and end of each lines dotAllLet . match line breaks toou unicodeTreat emoji as whole characters and allow \p classesy stickyOnly match right where the previous match ended

Common patterns

Test text

Matches

Enter a regular expression or pick a common pattern

Replace preview

Replace with

$1 group 1$<name> named group$& whole match$$ a literal $

Enter a valid pattern and some test text to see the replaced text here

How to use

1
Write a pattern
Type a regular expression at the top or pick a common pattern. Turn on the flags you need, such as g for every match or i to ignore case.
2
Add test text
Paste the text to check. Matches are highlighted right away, and the match list shows each index and group.
3
Preview the replacement
Use $1, $& and friends in “Replace with” to reuse matched text, then copy the result.

Tips

Catastrophic backtracking
Nested quantifiers such as (a+)+ or (.*)* get exponentially slower on text that doesn’t match. Matching stops here after 1.5 seconds; rewrite the pattern before you use it in code.
Escaping in code
Enter the part between the slashes. In a JavaScript string (new RegExp("…")) every backslash has to be doubled, so \d becomes \\d.
Engine differences
This uses your browser’s JavaScript regex engine. Python, Java and PCRE share most of the syntax, but named groups, lookbehind and Unicode classes are written differently, so test again when you switch languages.