Regex Tester & Debugger
Test JavaScript regular expressions with live matches
How it works
- 1Enter your pattern
Type or paste your regex in the pattern box. Pick the flags you need (g, i, m, s, u).
- 2Add test text
Paste the string you want to test against. Matches update live.
- 3Inspect matches
See highlighted matches, capture groups, and total match count in real time.
About Regex Tester & Debugger
Free online regex tester for JavaScript regular expressions. See matches highlighted live as you type, view capture groups, test flags (g, i, m, s, u, y), and get match counts. Runs entirely in your browser — no signup, no ads inside the tool. Regex Tester & Debugger on 712 Tools runs entirely inside your browser using modern JavaScript APIs — no server ever sees your data. That means instant results, complete privacy, and no upload limits.
Whether you need to test javascript regular expressions with live matches for a debugging session, a quick sanity check, or a production incident, this tool is free to use as many times as you need. There are no watermarks, no sign-up, and no ads inside the tool itself.
Frequently asked questions
Which regex flavor is this?
JavaScript (ECMAScript) — the same regex engine that runs in your browser and Node.js.
Does it support named groups?
Yes. Named capture groups like (?<year>\d{4}) are shown alongside numbered groups in the results panel.
Is my pattern or text uploaded?
No. Everything runs in your browser via the native RegExp engine.
Why is my pattern hanging?
You may have hit catastrophic backtracking — a common issue with nested quantifiers like (a+)+. Simplify the pattern.
Read more
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Why your JSON won't parse (and how to fix it in 30 seconds)
Trailing commas, unquoted keys, single quotes, comments — the five errors that break 90% of hand-written JSON, and how to catch them without a build step.
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