Regex Tester
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Write a regular expression and test it against your text in real time. See highlighted matches, capture groups, and replace output, with every flag at your fingertips, all running privately in your browser.
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JavaScript regex engine. Runs entirely in your browser.
How to Use the Regex Tester
- Enter a pattern, type your regular expression between the slashes.
- Set flags, toggle global, case-insensitive, multiline, and more.
- Add test text, matches highlight live as you type.
- Inspect groups and replace, review capture groups and preview replacements.
Regex Quick Reference
\ddigit,\wword char,\swhitespace,.any char.*zero or more,+one or more,?optional,{n,m}range.^start,$end,\bword boundary.(...)capture group,(?<name>...)named group,(?:...)non-capturing.[abc]character set,[^abc]negated set,a|balternation.
Next steps
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Regex Tester: FAQ
What does this regex tester do?
It lets you write a regular expression and test it against sample text in real time. Matches are highlighted, capture groups are listed, and you can toggle flags like global, case-insensitive, and multiline to see exactly how your pattern behaves.
Which regex flavor does it use?
It uses the JavaScript (ECMAScript) regular expression engine, the same one that runs in browsers and Node.js. Patterns you test here will behave identically in your JavaScript and TypeScript code.
Does it show capture groups?
Yes. For each match the tool lists numbered capture groups and named groups, so you can confirm your parentheses capture the right substrings before using the pattern in code.
What do the flags mean?
g matches all occurrences, i ignores case, m makes ^ and $ match line starts and ends, s lets the dot match newlines, u enables full Unicode, and y anchors matching to the last index. Toggle them to match your runtime configuration.
Can it generate replacement output?
Yes. Enter a replacement string with $1, $2, or named group references and the tool shows the result of running replace on your test text, which is handy for building find-and-replace rules.
Is it safe to test long patterns?
Testing runs locally in your browser. Be aware that catastrophic backtracking in a poorly written pattern can be slow regardless of the tool, so simplify nested quantifiers if matching hangs.
Is my data private?
Yes. Your pattern and test text never leave your browser. Nothing is uploaded to Web Aloha servers.
Is this regex tester free?
Yes. It is free, private, needs no signup, and works on desktop and mobile.
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