JavaScript regex (ECMAScript). Lookaheads, lookbehinds, character classes, capture groups, named groups all supported.

What is the safety limit?

Caps at 100,000 matches per run to prevent runaway patterns.

Regex Tester

Test JavaScript regular expressions live — see matches highlighted in your text and captured groups in a list.

How to use Regex Tester

Type your regex pattern.
Pick flags.
Paste test text — matches highlight live.

What is Regex Tester?

Build and debug regular expressions quickly: type a pattern, toggle flags (g, i, m, s, u), and see matches highlighted in your test text. Captured groups appear next to each match for easy verification.

FAQ

Which regex flavor?: JavaScript regex (ECMAScript). Lookaheads, lookbehinds, character classes, capture groups, named groups all supported.
What is the safety limit?: Caps at 100,000 matches per run to prevent runaway patterns.

Related tools

Find and Replace
Count Occurrences
JSON Formatter / Validator