Regex Tester
Test regular expressions against strings with live match highlighting.
Frequently Asked Questions
What are Regular Expressions?
A regular expression (regex) is a sequence of characters that specifies a search pattern. They are extremely powerful tools used in almost all programming languages for string searching, manipulation, and input validation (like checking if an email is formatted correctly).
What do the flags mean?
Flags modify how the pattern is matched.g (global): Find all matches rather than stopping after the first.i (ignore case): Makes the whole expression case-insensitive.m (multiline): Changes behavior of ^ and $ to match the start/end of each line.s (dotall): Allows the dot . character to match newline characters as well.
Which Regex flavor is this?
This tool runs on standard JavaScript (ECMAScript) RegExp. While highly similar to PCRE (PHP/Perl) or Python regex, it has some minor differences regarding advanced lookbehinds and named capture groups depending on your browser.