Best Free Regex Tester
Test a regular expression against your text live, with match and group highlighting.
100% free
No signup
No watermark
Files processed in memory, never stored
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How it works
- Enter a pattern. Type your regular expression and any flags (g, i, m, s, u).
- Paste test text. Add the text to run it against; matches highlight live as you type.
- Read the matches. See the count, the highlighted matches, and any capture groups.
About this tool
Build and check a regular expression against real text and watch the matches highlight as you type. Enter the pattern and flags, paste your test text, and every match is marked inline with the capture groups listed below — so you can see immediately whether the regex does what you intend. It uses your browser’s own JavaScript regex engine, so the behaviour matches what you’ll get in JS, and nothing is sent anywhere. Advanced options explain the flags (global, ignore-case, multiline, dotall, unicode).
What people use it for
- Check a regex matches what you expect before shipping it
- Debug a pattern that isn’t catching the right text
- See capture groups for a complex expression
- Learn regex by experimenting with instant feedback
Frequently asked questions
Your browser’s JavaScript regular-expression engine, so results match ECMAScript regex exactly — handy when you’re writing regex for JS or a web app.
g matches globally, i ignores case, m makes ^ and $ match line ends, s lets . match newlines, and u enables full unicode. Advanced options show this reminder.
Yes — each match’s numbered capture groups are listed below the highlighted text so you can see exactly what was captured.
No. Everything runs locally in your browser, so nothing you type leaves your device.
The pattern isn’t valid JavaScript regex — often an unescaped bracket or parenthesis. The error message points at what the engine objected to.
Yes — a client-side tool, no account, no limits, nothing stored.
Yes. It runs in your browser, so Regex Tester works on phones and tablets as well as desktop — there is no app to install.
Usually just a few seconds for a typical file — Regex Tester starts working the moment you give it your input.
Casual use is unlimited, under a generous fair-use cap that keeps it fast for everyone.
All modern browsers — Chrome, Safari, Firefox and Edge. Regex Tester needs nothing installed beyond the browser you already use.