Regex Tester
Test regular expressions and highlight matches in real time
About Regex Tester
Regex Tester lets you test regular expressions and highlight matches in real time.
Category: Text.
Frequently asked questions
What regex flavor does this use?
▾
JavaScript's RegExp engine (V8). This matches what you'd use in Node.js and browser JS. It differs from PCRE (Python, PHP, Ruby) — notably, JS doesn't support lookbehind assertions below ES2018 or atomic groups.
What are the available flags?
▾
g (global — find all matches), i (case-insensitive), m (multiline — ^ and $ match line boundaries), s (dotAll — dot matches newlines), u (full Unicode support).
What's the difference between a match and a capture group?
▾
A match is the full text the regex matched. A capture group (parentheses) extracts a sub-portion. Named groups (?<name>...) let you reference them by name instead of index.
How do I match a literal dot, slash, or bracket?
▾
Prefix special characters with a backslash to match them literally. For example, a backslash before a dot matches a literal dot; without it, a dot matches any character.