Test a regular expression with live highlighting and capture groups. Free, runs entirely in your browser — your files are never uploaded.
How to use Regex Tester
Enter your pattern and any flags.
Paste the text to test it against and watch matches highlight as you type.
Inspect the capture groups for each match.
Frequently asked questions
Which flavour of regex is this?
JavaScript’s, since it runs in your browser. It is close to PCRE for everyday patterns, though lookbehind and some Unicode property escapes differ from other languages.
What do the flags mean?
g finds every match rather than the first, i ignores case, m makes ^ and $ match at line boundaries, and s lets a dot match newlines.
Why does my pattern match nothing?
Most often an unescaped special character. Dots, plus signs, question marks, parentheses and brackets all mean something in a pattern and need a backslash to match literally.
Are capture groups shown separately?
Yes. Each match lists its groups, which is usually the quickest way to see why a pattern captures more or less than you intended.