How to test a regular expression
Test and debug regular expressions against sample text in your browser, with live match highlighting.
A regex tester runs your pattern against sample text and highlights the matches and capture groups live, so you can refine it without writing code. For example, the pattern \b\d{3}-\d{4}\b matches "555-1234" in "Call 555-1234".
Input
pattern: \b\d{3}-\d{4}\b · text: Call 555-1234Output
match: 555-1234
\d is a digit, {3} and {4} are counts, \b is a word boundary.
Open the Regex Tester → Free · runs in your browser · nothing uploaded
Steps
- Open the Regex tool and type your pattern (and any flags like g, i, m).
- Paste the sample text to test against.
- See matches highlighted live, along with any capture groups.
- Tweak the pattern until only the intended text matches.
Frequently asked questions
- What do the regex flags g, i, and m mean?
- g (global) finds all matches rather than just the first; i (ignore-case) makes it case-insensitive; m (multiline) makes ^ and $ match at line breaks rather than only the start/end of the whole string.