Regex Tester
Build and debug regular expressions against your own text. Matches are highlighted as you type, capture groups are listed for each match, and you can preview a replacement.
How to test a regular expression
- 1Type your pattern and choose flags such as global or ignore case.
- 2Paste the text to test against.
- 3Check the highlighted matches and groups, and preview a replacement if you need one.
JavaScript syntax
Patterns use JavaScript's regular expressions, as in browsers and Node.js, including lookbehind, named groups (?<name>…) and Unicode property escapes like \p{L} with the u flag.
Groups and replacements
Each match lists its numbered and named groups. In the replacement, $1 inserts group 1, $<name> a named group and $& the whole match, the same as String.replace.
Safe from runaway patterns
Some patterns, such as (a+)+$, can take forever on certain text. Matching runs separately from the page and stops after 2 seconds, so a bad pattern never freezes your browser.
Frequently asked questions
- Is my text uploaded?
- No. Matching runs in your browser.
- Why does my pattern from Python or PHP behave differently?
- Each language has small differences. Possessive quantifiers and some inline flags aren't supported in JavaScript, for example.
- How many matches are shown?
- Up to 1,000 matches are found and the first 100 are listed in detail.