Regex Tester
Test JavaScript regular expressions with real-time match highlighting and flag controls.
Test and debug JavaScript regular expressions in real time. Customize regex flags (g, i, m), test against multi-line sample strings, see match counts, and inspect match indexes instantly in your browser.
About Regex Tester & Matcher
Regular expressions are notoriously tricky to write without instant feedback. Regex Tester allows developers to construct, test, and debug patterns interactively before committing them to code.
How to Use Regex Tester & Matcher
- Enter pattern: Type your regular expression pattern (e.g. \d{3}-\d{3}-\d{4}).
- Set flags: Configure flags like g (global) or i (case-insensitive).
- Enter test text: Type or paste the sample text you want to test against.
- Inspect matches: See all matched substrings and their index positions.
Key Features
- Real-time regex evaluation
- Customizable flags (g: global, i: case-insensitive, m: multi-line)
- Live match counter and match list
- Safe sandbox execution
- 100% private
Common Use Cases
- Validating form input patterns for emails, phone numbers, and zip codes.
- Testing text scraping and parsing patterns for data ingestion scripts.
- Debugging URL routing expressions for web frameworks.
Frequently Asked Questions
Which regex dialect is used?
This tool uses the standard ECMAScript / JavaScript regular expression engine built natively into your browser.
What does the "g" flag do in regex?
The "g" (global) flag finds all matches throughout the text rather than stopping after the first occurrence.
Are my proprietary logs or test strings uploaded anywhere?
No. The regular expression runs strictly in your browser’s local JavaScript sandbox.
Can I test multi-line patterns in this tool?
Yes! Enabling the "m" (multi-line) flag causes the ^ and $ boundary anchors to match the start and end of each individual line within sample text.
Privacy Guarantee
100% client-side execution in your browser.
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