Regex Tester
Instant matches with flags (g/i/m/s)
Toggle flags; results update instantly.
Usage
Enter a regex pattern and text; matches are highlighted instantly.
Flags
gglobal searchiignore casemmultiline (^/$ match each line)sdot matches newline
Basics
.any single character*zero or more of previous+one or more?zero or one / lazy[]character class()group|alternation^start,$end of line
Example: ^hello.*$ matches lines starting with "hello".
FAQ
Lookbehind (?-<=) support?
Yes. Modern browsers support ES2018 lookbehind assertions.
Make ^/$ work per line
Enable the m (multiline) flag so ^ and $ match line starts/ends.
Dot matches newline?
Enable s (dotAll) so . matches newlines too.
Performance tips
Very large texts or complex patterns may be slow. Consider splitting input.