Regex Match & Replace Tester

Test regular expressions safely before using them in code. Type a pattern, toggle global/case-insensitive/multiline flags, see every match highlighted live, and preview find-and-replace results instantly.

How to Use

1. Type your regular expression in the pattern box and toggle the g/i/m flags.
2. Paste test text below to see every match highlighted live with a match count.
3. Enter replacement text (with $1, $2 back-references) to preview find-and-replace.

Core Features

• Live match highlighting with total match count
• Global, case-insensitive and multiline flag toggles
• Find-and-replace preview supporting capture-group references
• Clear invalid-regex error messages - 100% client-side

Frequently Asked Questions

What do the g, i and m flags do?

g finds all matches instead of stopping at the first, i makes matching case-insensitive, and m lets ^ and $ match at line boundaries instead of just the start/end of the whole text.

How do capture groups work in replacement?

Wrap part of your pattern in parentheses, like ([a-z]+)@, then reference it in the replacement box as $1. $2 refers to the second group, and so on.