Regex Tester — Test Regular Expressions Live
Free regex tester. Test JavaScript regular expressions with live match highlighting, capture groups, flags and a replace preview.
Runs in your browser — your data is never uploaded.
Write a regular expression and see matches highlighted in your test text as you type. The tool lists every match with its position and capture groups, supports the common flags (global, ignore case, multiline, dotAll and unicode) and previews the result of a replacement. It uses JavaScript regex syntax.
How to use the Regex Tester
- Enter your pattern and choose flags.
- Paste the text to test.
- Review highlighted matches and groups.
Regex Tester — frequently asked questions
Which regex flavour is used?
JavaScript (ECMAScript). Most basics are shared with other languages, but some features differ.
What do the flags mean?
g finds all matches, i ignores case, m treats lines separately, s lets . match newlines and u enables Unicode.
Why do I get no matches?
Check escaping (for example \d for digits) and whether the right flags are enabled.
Related free tools
Find and Replace
Free online find and replace. Replace words or patterns in bulk with optional regular expres…
Text Diff Checker
Free text diff checker. Compare two texts or files line by line and see additions and deleti…
JSON Formatter & Validator
Free JSON formatter and validator. Beautify, minify and validate JSON with clear error messa…
Have an idea? Let’s build it.
Tell us what you need — we’ll reply with a clear, written quote. No pressure, no jargon.