Skip to content
Regex Runs offline

Regex Tester

Test regular expressions live, with highlighted matches and groups.

g i m s u y

Mode

Input

0 chars

Output

0 chars
Ctrl↵

        
Questions
Which regex flavour is this?
JavaScript (ECMAScript), because matching runs in your browser. It is close to PCRE for everyday patterns, but there are differences: no possessive quantifiers, no atomic groups, no recursion, and lookbehind requires a reasonably modern browser.
Why is there an input size limit?
A pattern with nested quantifiers can backtrack catastrophically, taking exponential time on input that looks harmless. Since matching runs on the main thread, that would freeze the tab. Patterns are capped at 1 KB and the test string at 100 KB, which keeps worst-case matching survivable.
What do the flags do?
g finds all matches rather than stopping at the first, i ignores case, m makes ^ and $ match at line boundaries, s lets . match newlines, and u enables full Unicode handling. The tester enables g by default so you see every match.
        
Open Sort Lines
Sort Lines
Sort lines alphabetically, numerically, by length or at random.
Text