TL;DR — write a regex, paste text, see matches live
Type a pattern, toggle flags, and preview Match, Replace, or Split in real time. See start/end indexes and capture groups, export CSV, and save snippets. Runs 100% in your browser.
Regex Tester — free online regular expression testing tool
A fast, no‑login online regex tester for everyday regular expression testing. Type a pattern, toggle flags, and watch matches highlight instantly. Switch tabs to preview Match, Replace, or Split. The matches panel lists each hit with start/end indexes and capture groups, so you can debug quickly without leaving the browser.
Prefer a regex creator feel? Use presets (email, URL, dates, phone, IPv4), read the token‑by‑token explanation, and skim the built‑in cheat sheet. Save your own snippets for reuse or export results to CSV. Everything runs locally with the JavaScript RegExp engine, making this a practical regex checker, editor, and quick builder in one.
Applying patterns to full documents? Try Find & Replace. Extracting web addresses? Use the URL Extractor. Cleaning inputs first? Text Cleaner helps a ton.
Quick start
- Enter a pattern (e.g.
/\\w+/gor just\\w+) and toggle flags (g,i,m,s,u,y). Or pick a preset to begin faster. - Paste a test string. Use Match to highlight hits, Replace to preview substitutions (with
$1,$2…), or Split to segment text. - Inspect the Matches table for indexes and groups, export CSV, copy your pattern, or save a named snippet for later.
Key features
- Live Match / Replace / Split previews
- Start & end indexes plus capture groups for each hit
- Token‑by‑token explanation of your pattern
- Presets: email, URL, date, phone, IPv4
- Cheat sheet and user‑saved snippets
- CSV export of matches; one‑click copy of regex and results
- Undo/redo for pattern edits; flag toggles (g/i/m/s/u/y)
- 100% client‑side — fast, private, and offline‑friendly
Tips
- Start simple; add anchors (^, $) and quantifiers gradually.
- Use non‑capturing groups (?: … ) when you don’t need backreferences.
- Prefer explicit character classes over dots when possible.
- Test edge cases: empty lines, Unicode, and newlines (try the s and m flags).
- Beware zero‑length matches; ensure your pattern advances through the string.
Frequently asked questions
Which regex flavor does this use?
Can I use it as an online regex builder?
Why don’t my results match another tester?
dotAll, multiline, Unicode). Double‑check flags and flavor specifics when comparing.Is my data private?
You might also like
- Apply patterns across whole documents with Find & Replace.
- Extract and decode links using URL Extractor and URL Encoder / Decoder.
- Prep messy inputs before testing with Text Cleaner.
Last updated: Aug 12, 2025