Regex Tester

About Regex Tester

Free online regex tester. Write and test JavaScript regular expressions with real-time match highlighting, captured group inspection, and flag toggles (g, i, m, s, u). See all matches highlighted directly in your test string. Essential for developers working with pattern matching, form validation, and text parsing.

How to Use Regex Tester

1. Enter your regular expression in the Pattern field (without surrounding slashes).
2. Select the flags you need: g (global), i (case-insensitive), m (multiline), s (dotAll), u (Unicode).
3. Paste your test string into the Test String field — all matches highlight in real time.
4. Check the Matches panel below to see each individual match, its position, and any captured groups.

Frequently Asked Questions

What regex flavor does this tester use?

This tester uses JavaScript's built-in RegExp engine, which follows the ECMAScript standard. It supports standard regex syntax plus Unicode property escapes (\p{}) with the u flag.

What do the regex flags mean?

g = global (find all matches, not just the first), i = case insensitive, m = multiline (^ and $ match line boundaries), s = dotAll (. matches newlines too), u = Unicode mode (enables \p{} property escapes).

How do I match a literal dot or other special character?

Escape it with a backslash. For a literal dot: \. For a literal backslash: \\. Special regex characters that need escaping: . * + ? ^ $ { } [ ] | ( ) \

Why does my regex not find a second match?

Without the g (global) flag, regex stops after the first match. Enable the g flag to find all occurrences in the test string.