Regex Tester
Test and debug regular expressions with live matching and highlighting.
"support@example.com"pos 14–33"sales@konvertio.app"pos 37–56Frequently Asked Questions
What is a regular expression?
A regular expression (regex) is a sequence of characters that defines a search pattern. It is used for pattern matching within strings — finding, replacing, or validating text. Regexes are supported in virtually every programming language.
What do the regex flags mean?
g (global) finds all matches instead of stopping at the first. i (case-insensitive) ignores letter casing. m (multiline) makes ^ and $ match the start/end of each line. s (dotAll) makes the dot (.) match newline characters as well.
Why is my regex not matching?
Common issues include forgetting the global flag (g) to find all matches, not escaping special characters like . or *, and incorrect character class syntax. This tool shows errors in real time to help you debug.
What are capturing groups?
Capturing groups are parts of a regex enclosed in parentheses (). They capture the matched text for back-references or extraction. Non-capturing groups (?:...) group without capturing, which can improve performance.
How do I match special characters literally?
Escape special regex characters with a backslash: \. matches a literal period, \* matches an asterisk, \[ matches a bracket, etc. Inside a character class [...], most special characters lose their meaning except ] \ ^ -.