Regex Tester Converter
Test a pattern against real text and see every match.
Test text
Matches
About the Regex Tester converter
Write a pattern, paste some text, and see exactly what matches — with the line number, the character index and the contents of every capture group.
The engine is your browser's own, so the behaviour is identical to what your JavaScript or TypeScript code will do.
Flags
`g` finds every match rather than stopping at the first — it is added automatically here. `i` ignores case. `m` makes `^` and `$` match at line boundaries instead of only at the ends of the string. `s` lets `.` match a newline. `u` enables full Unicode handling, which you need for emoji and non-Latin scripts.
Capture groups
Parenthesised groups are listed under each match as `$1`, `$2` and so on. Named groups written `(?<name>…)` appear by name.
In replacement mode you can reference them the same way: `$1` inserts the first group, `$&` the whole match.
Patterns that hang
Nested quantifiers such as `(a+)+b` can take exponential time on input that nearly matches — catastrophic backtracking. If a pattern seems to freeze the page, that is almost certainly the cause. Make the inner quantifier possessive by restructuring, or anchor the pattern more tightly.
Frequently asked questions
Do I include the slashes?
No. Write the pattern body only and put the flags in the separate field.
Is this the same as PCRE or Python re?
No — it is the JavaScript flavour. Lookbehind is supported in modern browsers, but recursion, possessive quantifiers and atomic groups are not.
Can I test against a log file?
Yes, upload it to the input panel. Everything stays on your device.