About this regex tester
A regular expression (regex) is a compact pattern for finding text — a run of digits, an email shape, a word at the start of a line, and so on. This regex tester lets you write a pattern and immediately see what it matches in your sample text: every match is highlighted, counted, and listed with its position and any capture groups it contains. The four checkboxes map to the standard JavaScript flags — g finds all matches instead of just the first, i ignores upper and lower case, m makes ^ and $ work on each line, and s lets . match newlines. If your pattern has a syntax error, the tool explains what went wrong instead of failing silently. Matching uses your browser's own regular-expression engine and nothing you type is sent anywhere.
Frequently asked questions
- What regex flavour does this use?
- It uses JavaScript's built-in regular-expression engine, the same one that runs in every web browser, so patterns behave exactly as they would in JavaScript code.
- What do the g, i, m and s flags do?
- g finds every match rather than the first, i ignores case, m makes ^ and $ match at line breaks, and s lets the dot match newline characters.
- Is my text sent to a server?
- No. The pattern and text are matched entirely in your browser, so nothing you paste ever leaves your device.