Regex Tester
Test and debug regular expressions online with real-time match highlighting, capture groups, and a quick-reference cheat sheet. Free, instant.
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Frequently asked
questions
A regular expression (regex) is a pattern used to match character combinations in strings. It is used in programming for search, validation, and text manipulation.
g (global) — find all matches, not just first. i (case-insensitive) — match regardless of case. m (multiline) — ^ and $ match line starts/ends. s (dotAll) — dot matches newlines too.
Parentheses in regex create capture groups. For example, (\d{4})-(\d{2})-(\d{2}) on "2024-01-15" captures "2024", "01", and "15" as separate groups you can reference.