Regex Tester
✓ Link copiedBuild and test regular expressions in real time. Enter a pattern, toggle flags like global, ignore-case, and multiline, then paste a test string to see every match highlighted instantly. Inspect each match's position, numbered capture groups, and named groups, and get a clear, friendly message when a pattern is invalid. Free, fast, and runs entirely in your browser; your data never leaves your device.
How to use
Type your regular expression in the Pattern box and toggle the flags you need (g, i, m, s, u, y). Paste the text you want to test below — matches are highlighted live as you type, with a running match count. Each match is listed with its position and any capture groups, both numbered and named. An invalid pattern shows a clear error message instead of breaking.
Frequently asked questions
- Is the regex tester free?
- Yes. It's completely free, needs no sign-up, and runs entirely in your browser.
- Which regex flavor and flags are supported?
- It uses your browser's native JavaScript (ECMAScript) regular expression engine, with support for the g (global), i (ignore case), m (multiline), s (dotall), u (unicode), and y (sticky) flags, plus numbered and named capture groups.
- What happens when my pattern is invalid?
- Nothing breaks. The tool catches the error and shows a clear message describing what's wrong, so you can fix the pattern and keep testing.