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Regex Tester
Test regular expressions with real-time match highlighting. Browse 15+ pre-built patterns for common use cases.
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//g
Flags:
0 matches
Match Details
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What is Regex Tester?
StackPro's Free Regex Tester is a developer-focused tool for building, testing, and debugging regular expressions with real-time match highlighting. Paste your test string, write a regex pattern, and instantly see all matches highlighted with detailed match information including groups and indices. The Pattern Library tab provides 15+ pre-built, tested regex patterns for common tasks like email validation, URL matching, phone numbers, dates, IP addresses, and more — click to load into the tester instantly.
How to Use Regex Tester
- Enter your regular expression pattern in the regex input field.
- Toggle flags (global, case-insensitive, multiline, etc.) as needed.
- Paste or type your test string in the textarea below.
- View real-time match highlights and match details in the results panel.
- Use the Pattern Library tab to browse and load pre-built regex patterns.
Features
- Real-time match highlighting as you type
- Flag toggles: global, case-insensitive, multiline, dotAll, unicode
- Detailed match panel with groups, indices, and capture info
- Find-and-replace testing with capture group references
- Pattern Library with 15+ pre-built tested patterns
- Quick reference sidebar with regex cheatsheet
- Pattern history (last 20 tests)
- Permalink generator for sharing patterns
Frequently Asked Questions
What is the Pattern Library?▼
The Pattern Library contains 15+ pre-built, tested regular expressions for common use cases like email validation, URLs, phone numbers, dates, IP addresses, and more. Each pattern includes a description, the regex, flags, and example matches. Click "Use this" to instantly load any pattern into the tester.
What regex flavors are supported?▼
The tester uses JavaScript's built-in RegExp engine, which supports ECMAScript regex syntax including lookaheads, lookbehinds, named groups, and Unicode property escapes.
Can I test regex replacements?▼
Yes! The replace tab lets you test find-and-replace operations with capture group references ($1, $2, etc.). See the replacement result update in real-time as you modify the pattern or replacement string.
Is there a regex cheatsheet?▼
Yes, a quick reference sidebar displays common regex tokens, quantifiers, character classes, anchors, and groups with descriptions and examples. Perfect for learning or quick lookups while building patterns.