Test regular expressions with live match highlighting, capture groups, replace mode, and match count — free, no signup, instant results.
g global · i case-insensitive · m multiline · s dotAll · u unicode
Type your regular expression in the pattern field (without delimiters). Add flags like g, i, m in the flags field.
Enter the string you want to test in the test area. Matches are highlighted live as you type — no button needed.
Switch to Replace mode to run regex replace with group references ($1, $2). Switch to Groups to inspect all capture groups per match.
This tester uses JavaScript's built-in RegExp engine — the same regex flavor used in Node.js, Chrome DevTools, and all modern browsers. It supports lookahead/lookbehind (ES2018+), named capture groups, and the s (dotAll) flag. PCRE-specific features like (?P<name>) are not supported — use (?<name>) for named groups instead.
Use $1, $2, etc. to reference capture groups in the replacement string. For example, pattern (\w+)\s(\w+) with replacement $2, $1 will swap two words. For named groups, use $<name>. Use $& to insert the whole match.
regex101 is great but requires an account to save patterns and is more complex than most developers need. This tester is a clean, fast, no-signup alternative for everyday JavaScript regex testing — match highlighting, replace mode, and group inspection all in one page.