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Test and debug regular expressions in real-time with match highlighting, capture groups, and detailed match information.
Enter a PCRE-compatible regex pattern without delimiters.
Matches will appear here with position, group, and capture group information.
g (global), i (case-insensitive), m (multiline), and more.Tip
Click Load Example to try a sample regex for extracting email addresses from text.
A regular expression (regex) is a sequence of characters that define a search pattern. They are used for pattern matching, text validation, search-and-replace operations, and data extraction. This tool uses JavaScript's RegExp engine which is compatible with PCRE syntax.
g (global) — Find all matches, not just the first. i — Case-insensitive matching. m (multiline) — ^ and $ match the start/end of each line. s (dotall) — Dot matches newlines. u (unicode) — Treat pattern and text as unicode. x (extended) — Ignore whitespace and comments in the pattern.
Capture groups are parts of a pattern enclosed in parentheses (). They "capture" the matched portion so you can extract specific parts. For example, (\w+)@(\w+) captures the username and domain separately from an email.
JavaScript's RegExp engine is broadly compatible with PCRE (PHP) syntax for most common patterns. However, some PCRE-specific features like \K, possessive quantifiers, and recursive patterns may not work. For basic to intermediate patterns, the results will be the same.
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