Test regular expressions against any text. See all matches, capture groups, and indexes live as you type.
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Knowledge Base
A regular expression (regex) is a sequence of characters that defines a search pattern. They are used for string matching, validation, and text manipulation in virtually every programming language.
The 'g' flag finds all matches (not just the first). 'i' makes matching case-insensitive. 'm' makes ^ and $ match line starts/ends. 's' (dotAll) makes the dot (.) also match newline characters.
Capture groups are parts of a regex wrapped in parentheses, e.g. (\d+). When a match is found, the text matched by each group is extracted separately, which is useful for parsing structured data.
Yes. Use the Quick Patterns dropdown to load pre-built patterns for common formats like email addresses, URLs, phone numbers, dates, and IP addresses, then adjust them to your needs.