Test regular expressions against sample text with live match highlighting, capture group extraction, and flag controls (global, multiline, case-insensitive). All evaluation runs client-side, meaning no data leaves your browser.
Key Features of Regex Tester
- Live Match Highlighting See instantly matching text highlighted on the fly as you modify your regular expression or test string.
- Interactive Flags Toolbar Easily toggle global (g), case-insensitive (i), multiline (m), and dotAll (s) flags to alter matching behaviors.
- Capture Group Extraction Isolate match indexes, full match contents, and detailed capture group mappings in a structured inspector panel.
- Client-Side Evaluation Run tests securely; all regular expression compilations occur locally inside your browser's execution thread.
Regex Tester Examples
Validating Email Addresses
Extract or validate emails from strings using standard pattern recognition.
Input
Pattern: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}
Test Text: Please send inquiries to support@yoraba.com or sales@yoraba.com.Output
Matches found: 2
1. support@yoraba.com
2. sales@yoraba.comParsing URLs
Parse standard URL structures into capture groups (protocol, domain, path).
Input
Pattern: (https?):\/\/([^\/\s]+)([\/\w \.-]*)*
Test Text: Visit https://yoraba.com/tools/regex-tester for details.Output
Match 1: https://yoraba.com/tools/regex-tester
Group 1: https
Group 2: yoraba.com
Group 3: /tools/regex-testerHow to Use Regex Tester
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1. Enter Your Regex Pattern
Type your regular expression pattern into the pattern field, including any flags (g, i, m, s).
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2. Paste Your Test String
Enter the text you want to test against in the test string area below.
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3. View Matches in Real Time
All matches are highlighted as you type, with match count and capture group details shown.
Common Use Cases for Regex Tester
- Debugging Custom RegEx Patterns Troubleshoot validation patterns for web forms (passwords, phone numbers, zip codes).
- Data Extraction & Scraper Formatting Isolate specific numbers, HTML tags, or string keys from larger document fragments.
- Text Cleanup & Replacement Planning Draft search-and-replace queries to format CSV records or unorganized configuration files.
The Technical Details
The Regex Tester compiles regular expressions using the host browser’s built-in RegExp object constructor. Evaluations are performed instantaneously inside a reactive UI loop.
To guarantee a smooth interface, match locations are extracted using the global matching method String.prototype.matchAll (when the global flag ‘g’ is active). Highlighting is achieved by parsing the target string into segments of matched and non-matched boundaries, then dynamically embedding them into read-only overlay containers. This approach completely prevents layout distortion and maintains absolute data confidentiality because no server calls are made.
Frequently Asked Questions
Which regex flags are supported?
The tool supports all JavaScript regex flags: g (global), i (case-insensitive), m (multiline), s (dotAll), and u (unicode).
Are lookaheads and lookbehinds supported?
Yes. Positive and negative lookaheads and lookbehinds are supported in all modern browsers.
Is any data sent to a server?
No. All regex matching runs in your browser using the native JavaScript RegExp engine.
Where can I find common regex patterns?
Check the Regex Patterns cheatsheet on this site for ready-to-use patterns for emails, URLs, dates, and more.