Most quick regex testers highlight matches by search-and-replacing the matched text with a wrapped version of itself — which works fine until your sample text contains regex metacharacters, HTML-like fragments, or anything else that trips up a naive string replace. Our new Regex Tester highlights matches by slicing the original string around each match’s position instead, so it stays correct no matter what you paste.
- Live everything — pattern, flags, and sample text all update the result as you type, with a running match count.
- All five flags — g, i, m, s, and u, each with a plain-language explanation of what it changes, right on the page.
- Real capture groups — every match lists the text captured by each parenthesized group, with unmatched groups shown explicitly rather than as blank strings.
- Shareable patterns — the pattern and flags sync to the URL, so you can send a colleague a link that opens pre-loaded with your regex. Your sample text never goes in the URL, since people often paste real data — logs, emails, IDs — in there.
- Honest errors — an invalid pattern shows the JavaScript engine’s own error message in a plain-language wrapper, not a guess.
- Private by default — matching runs with a native
RegExpin your own browser; nothing you type is ever sent to a server.
Try the classic (\w+)@(\w+)\.com against a block of text with a few
email addresses, or bring in whatever pattern you’re actually
debugging — and if you maintain developer docs, the tester is
embeddable on your own site with one iframe.