Free online regex tester
Test regular expressions in your browser with live matches, flag toggles, highlighted previews, and capture groups. Paste a pattern and a test string to debug email validation, log parsing, search filters, and replacements - privately, with nothing uploaded.
What you can do
Live matching
See every match update as you edit the pattern, flags, or test string - no server round trip.
Flags & groups
Toggle g, i, m, s, u, and y. Inspect numbered capture groups and named groups for each match.
Private by default
Patterns and test data stay in your browser. Ideal for debugging logs, validators, and scrapers.
How to use this regex tester
- Enter a regular expression in the pattern field (without surrounding slashes).
- Toggle flags such as g (global) and i (case-insensitive) as needed.
- Paste your test string - or click Sample for a quick example.
- Review matches, indices, and capture groups on the right; use the highlighted preview.
- Copy matches when you want the list on your clipboard.
Quick regex cheat sheet
.- any character (except newline unlesssis on)\d\w\s- digit, word character, whitespace^/$- start / end (of string, or line withm)*+?{n,m}- quantifiers(abc)- capturing group;(?:abc)- non-capturing[a-z]/[^0-9]- character class / negated class
Deeper walkthroughs: Common regex mistakes and What is a regular expression?.
Frequently asked questions
Learn more about regular expressions
Related tools: Timestamp converter, JSON formatter, URL encoder.
Why use an online regex tester?
Regular expressions are powerful and easy to get wrong. A visual tester shortens the loop when you are writing validators, search filters, log parsers, or find-and-replace rules. Running matches locally keeps sample data on your machine while you iterate on the pattern - and confirms behavior in the same JavaScript RegExp engine many web apps use.