Is Regex Shuttle free?

Yes, Regex Shuttle is completely free with no hidden costs. All features can be used without limits and without creating an account.

Are my regular expressions uploaded to a server?

No. All processing in Regex Shuttle happens locally in your browser using JavaScript's built-in RegExp engine. Your patterns and test data never leave your device.

What regex features are supported?

Regex Shuttle supports standard JavaScript regular expression features, including capturing groups, lookahead/lookbehind assertions, named capturing groups, and Unicode patterns. The flag toggles offer five commonly used flags: g (global, find all matches), i (case-insensitive), m (multiline, where ^ and $ match line boundaries), s (dotAll, where . matches newlines), and u (Unicode).

What languages does the Regex Explainer support?

Currently the Regex Explainer provides explanations in English. The interface supports both English and Chinese languages.

Can I use Regex Shuttle offline?

After the initial load, Regex Shuttle can work offline in your browser. All core features (testing, substitution, explanation) run entirely client-side and don't require a network connection.

What's the difference between Regex Shuttle and other online regex testers?

Regex Shuttle's key advantage is privacy — all processing happens locally in the browser with no data uploads. It also provides a complete toolset including a Regex Explainer, Pattern Library, substitution testing, and cheat sheet, all completely free with no registration required.

How does Regex Shuttle display capture groups?

Every match lists its capture groups individually. For numbered groups such as (\d+), Regex Shuttle shows the captured text along with its index position in the original string. For named capture groups such as (? \d{4}), the group name is shown alongside the text so you can verify your references are correct. When you use the global g flag, every match expands to show its own group details, letting you see exactly what the pattern captures across the entire input.

Why might Regex Shuttle's results differ from PCRE or Python?

Regex Shuttle uses the browser's built-in JavaScript RegExp engine, not PCRE, Python's re, or .NET. These dialects differ in syntax and behavior — for example, JavaScript has limited support for atomic groups, possessive quantifiers, and recursion, and it handles escapes and Unicode properties differently. The upside: what you test here is exactly the engine that Node.js and browsers run, so the results match production. If your code runs in another language, defer to that language's regex documentation.

About Regex Shuttle

A fast, private, browser-based regex testing and learning tool by ShuttleLab

What is Regex Shuttle?

Regex Shuttle is a free online regular expression testing, explaining, and learning tool that processes everything directly in your browser. Unlike other regex testers that may log your patterns or require account creation, Regex Shuttle uses modern web technologies to test and explain your regular expressions without ever leaving your device. Every regex execution, every match highlight, and every explanation is computed locally using JavaScript's built-in RegExp engine.

Built by ShuttleLab, Regex Shuttle supports all standard regex features including capturing groups, lookahead/lookbehind assertions, named groups, and Unicode patterns. Whether you need to validate user input, parse log files, extract data from text, or simply learn how regular expressions work, Regex Shuttle provides a comprehensive, zero-privacy-risk environment for all your regex needs.

100% Private

All regex processing happens locally in your browser. No patterns are uploaded, no data is collected, and no third parties can access your test strings.

No Account Required

Start testing immediately — no sign-up, no email, no tracking. Just paste your regex and go.

Developer Friendly

Built with developers in mind. Copy regex with flags, browse common patterns, and understand complex expressions with token-by-token explanations.

Lightning Fast

Real-time matching with 150ms debounce. See results as you type without any lag, even with complex patterns and large test strings.

Who uses Regex Shuttle?

🖥️

Backend Developers

Instantly test and debug regex patterns for server-side validation, log parsing, or data extraction without repeatedly running unit tests.

🌐

Frontend Developers

Preview regex matches in real-time while building form validation, input formatting, or text highlighting features.

📊

Data Analysts

Extract, replace, and restructure text fields when cleaning datasets. Process locally in your browser — your data never leaves your device.

🎓

Students & Beginners

Learn regex through token-by-token natural language explanations and instant match feedback. The built-in pattern library and cheat sheet help you get started quickly.

When should I use Regex Shuttle?

1
Validating user input (email, phone, URL)

Before: Write regex, deploy to server, test via API to check matches — long iteration cycle

After: Test in Regex Shuttle in real-time, iterate in seconds, copy directly to code when ready

2
Parsing server logs to extract key information

Before: Test regex with grep in CLI, repeatedly adjust parameters, results are not visual enough

After: Paste log samples, see highlighted matches with capture groups and index details

3
Understanding a complex regex written by a colleague

Before: Spend significant time reading regex docs, manually analyzing each character

After: Paste regex into the explainer, get token-by-token English explanation and overall summary

4
Batch find-and-replace in text data

Before: Use editor's find-replace, no capture group references, manual replacement one by one

After: Use substitution testing with $1, $2 capture group references, real-time replacement preview

5
Quickly finding common regex patterns

Before: Bounce between search engines and Stack Overflow, filtering outdated or unreliable answers

After: Browse built-in Pattern Library, filter by category, one-click copy or jump to tester

How-To Guides

How to test a regular expression

1Open the Regex Shuttle website (regex.shuttlelab.org)
2Type your regex pattern in the 'Regular Expression' field, e.g. \d+@[a-z]+\.com
3Paste or type the text to match against in the 'Test String' area
4View real-time highlighted matches, group information, and index positions

How to use the Pattern Library

1Navigate to the 'Pattern Library' page
2Browse by category: Common, Developer, Validation, etc.
3Click 'Copy Pattern' to copy the regex directly to your clipboard
4Click 'Test Pattern' to jump to the tester with the regex pre-filled

How to use the Regex Explainer

1Navigate to the 'Regex Explainer' page
2Enter any regex, e.g. ^(?=.*[A-Z])(?=.*\d).{8,}$
3View token-by-token English explanation and overall summary

Regex Shuttle vs Similar Tools (as of 2026-06)

Feature	Regex Shuttle	regex101.com	regexr.com
100% Local Processing	✓	✗	✗
No Registration Required	✓	✓	✓
Regex Explainer	✓	✓	✓
Substitution Testing	✓	✓	✓
Built-in Pattern Library	✓	✗	✗
Regex Cheat Sheet	✓	✗	✓
Offline Use	✓	✗	✗
Bilingual UI (EN/ZH)	✓	✗	✗
Completely Free	✓	✓	✓

Frequently Asked Questions

Love Regex Shuttle?

Regex Shuttle is crafted with care by ShuttleLab — completely free. If it has helped you debug even one regex, sharing it with fellow developers is the best support we could ask for.

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Get in Touch

Have questions, feedback, or need support?

support@shuttlelab.org