Regex Tester
Test a regular expression against your text and highlight every match — live, in your browser.
Regular expressions are powerful but fiddly, and the fastest way to get one right is to test it against real text. Regex Tester runs your pattern live against your input and highlights every match as you type, so you can build and debug a regex in your browser.
How to use regex tester
- 1. Enter your regular expression and flags.
- 2. Paste the text to test it against.
- 3. See every match highlighted live.
When to use Regex Tester
Build a pattern
Craft a regex step by step, watching the matches update as you refine it.
Debug a failing regex
See exactly what your pattern matches (or misses) in real text.
Learn regex
Experiment with patterns and flags to understand how they behave.
Frequently asked questions
Which regex flavour does it use?
JavaScript's regular expression engine, since it runs in your browser — with the usual flags like global and case-insensitive.
Does it show all matches?
Yes — matches are highlighted live in your test text as you edit the pattern.
Is my text uploaded?
No — the pattern runs entirely in your browser.