Regular expressions are easy to get almost right — a forgotten flag or a misplaced quantifier, and your pattern quietly matches the wrong thing. Our new regex tester is built to catch that fast:
- Live highlighting — every match is marked directly in your test string as you type.
- Capture groups, listed — each match shows its index and the text captured by every parenthesized group.
- All five JS flags — g, i, m, s, u — with dotAll (s) and unicode (u) available, not just the basics.
- Shareable patterns — the pattern and flags sync to the URL, so you can send a colleague a link that opens with your exact regex pre-loaded. Your test string is never included — only the pattern and flags travel in the link.
One honest note: this builds a native JavaScript RegExp, so it
follows JS regex rules specifically. Other tools and languages (PCRE,
Python’s re) have real syntax differences — a match here doesn’t
guarantee a match there.
The tester is also embeddable if you want a quick regex sandbox on your own docs or internal tools page.