Developers
Regex Tester
Your regular expressions tested live — matches highlighted, groups broken down.
| # | Matches | Capture groups |
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Writing a regular expression correctly on the first try, without testing it, is a gamble. This tester gives you instant feedback: enter your pattern, your flags and a sample text — every match is highlighted as you type, and captured groups are listed one by one with their contents. An unclosed parenthesis or invalid quantifier? The syntax error is shown clearly instead of failing silently. The engine is your browser’s own, meaning standard JavaScript syntax: whatever you validate here will work as-is in your front-end or Node.js code. Free, no sign-up, and your test data never leaves your machine — paste real samples with confidence.
How does it work?
- Enter your regular expression pattern and its flags (g, i, m…).
- Paste a representative sample into the test text area.
- Watch the matches light up and the capture groups get listed.
- Tweak the pattern until it behaves, then copy it into your code.
Frequently asked questions
Why doesn’t my regex match anything?
Check the classics first: an unescaped special character (a dot matches anything, “\.” matches a literal dot), a missing flag (without “i” case matters; without “m”, ^ and $ only apply to the whole text), or an over-greedy pattern — “.*” often swallows more than intended; prefer “.*?” or a negated character class.
What do the g, i and m flags do?
“g” (global) finds all matches instead of stopping at the first; “i” ignores case; “m” (multiline) makes ^ and $ match the start and end of each line rather than the whole text. There are others: “s” lets the dot match newlines, “u” enables full Unicode handling.
How do I extract a specific part of the match?
With capture groups: wrap the part you want in parentheses and it shows up here in the groups list. Named groups “(?<name>…)” make your code more readable; non-capturing groups “(?:…)” let you group without capturing, keeping the result clean.
Will my regex also work in PHP or Python?
The core syntax is shared, but every engine has quirks: lookbehind support and Unicode classes differ, PHP (PCRE) requires delimiters, Python uses re.MULTILINE rather than inline flags. This tester validates JavaScript syntax — retest in the target language if you rely on advanced features.