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Test regular expressions in real-time with live highlighting, match groups, pattern library, and regex cheat sheet. 100% browser-based, zero tracking.
Enter a pattern to see token explanations.
Regular expressions are powerful but unforgiving. The Regex Tester gives you real-time match highlighting, group extraction, and flag controls in a live editor — so you can build, test, and refine patterns against real data before embedding them in code.
g — Global: find all matches, not just firsti — Case-insensitive matchingm — Multiline: ^ and $ match line starts/endss — Dotall: dot matches newlines tooUse named capture groups (?<name>...) to extract labeled data from matches. They make patterns self-documenting and simplify the match result handling code.
Backtracking regex patterns on large inputs can cause catastrophic performance. Use the ReDoS Checker before using complex patterns in server-side code.
Global flag — returns all matches instead of stopping at the first. Essential for replacement and extraction operations.
Syntax (?<name>...) that assigns a label to a capture group, making match results easier to work with in code.
Yes. Use the m flag so ^ and $ anchor to individual line starts/ends rather than the full string.
Check out our technical guides to learn more about how browser-side processing works.
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