Regex Tester
Test regular expressions with live match highlighting.
Explanation
Plain-English breakdown of every token in the pattern
(start of a capture group\w+matches any word character (letter, digit or underscore), repeated one or more times)end of the group@matches the literal text "@"(start of a capture group\w+matches any word character (letter, digit or underscore), repeated one or more times)end of the group\.matches the literal character "."commatches the literal text "com"
g — global — find every match, not just the firstPattern library
Click any pattern to load it into the pattern field
Basics
Contact
Web
Dates & numbers
Dev & security
Logs & text
Test string
Capped at 20,000 characters to avoid catastrophic backtracking.
Highlighted matches
Capture groups
| # | Match | Index | Groups |
|---|---|---|---|
| 1 | ada@example.com | 9 | ada, example |
| 2 | alan@test.com | 26 | alan, test |
Replace preview
Export to code
Ready-to-paste snippet for the pattern, flags and replacement above
About the Regex Tester
Write and test regular expressions with live highlighted matches, a capture group table, a replace preview, and a cheatsheet of common patterns. Input length is capped to avoid catastrophic backtracking.
Examples
Email match
(\w+)@(\w+)\.comOutput
Matches ada@example.comKeyboard shortcuts
- Copy the main outputCtrl / ⌘ + Shift + C
- Download the resultCtrl / ⌘ + S
- Share this toolCtrl / ⌘ + Shift + S
- Reset the inputsAlt + R
- Open the tool search paletteCtrl / ⌘ + K
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Frequently asked questions
Read more
- Regex patterns every developer should know
A working set of regular expressions for emails, URLs, whitespace and validation — plus how to test them safely.
- Writing safer regular expressions: avoiding catastrophic backtracking
ReDoS bugs come from a small number of recognizable patterns. Here's how to spot them and write regexes that stay fast on any input.
- Regex lookahead and lookbehind in practice
What (?=...), (?!...), (?<=...) and (?<!...) actually do, with real patterns for passwords, numbers and text extraction.
- Testing a regex once, then shipping it in JavaScript, Python, Java and Go
Regex syntax is portable in theory and fiddly in practice. Here is how to test a pattern, read its groups, and export a working snippet for seven languages.
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Version 1.0.0 · Updated 2026-08-06 · Runs entirely in your browser