AIAZHHow To Use
- Enter Pattern — Type your regex pattern in the Pattern field. No server upload — all matching runs locally in your browser using JavaScript RegExp.
- Set Flags — Toggle flags (g, i, m, s) as needed for your search. Global matches all occurrences, case-insensitive ignores case.
- Input Test String — Type or paste your test string in the text area below the pattern.
- View Matches — See matches highlighted in real time in your test string, with a details table showing index and length for each match.
- Keep It Private — Your patterns and test data never leave your browser. Close the tab and it's gone — no server ever saw it.
Frequently Asked Questions
What is a regex tester online tool?
A regex tester online tool lets you write and test regular expressions against input text with instant visual feedback. It highlights matches in real time, shows match details like index and length, and supports JavaScript regex flags for precise pattern matching.
How does the regular expression tester work?
Enter your regex pattern and test string. The tool uses JavaScript's built-in RegExp engine to find matches instantly. Matches are highlighted in the test string, and a details table shows each match's text, starting index, and length.
What regex flags are supported?
The tool supports g (global — match all occurrences), i (case-insensitive), m (multiline — ^ and $ match line boundaries), and s (dotall — dot matches newlines).
Is my data kept private?
Yes. All regex testing happens locally in your browser using JavaScript's built-in RegExp engine. Your patterns and test strings are never sent to any server.
Can I use this as a regex validator?
Yes. The regex validator shows whether your pattern matches the test string and highlights exactly where matches occur. Invalid patterns display immediate error messages so you can fix syntax issues.
Real-Time Match Highlighting
See matches highlighted instantly as you type your regex pattern and test string.
Match Details Table
Each match shows full text, starting index, and length in an easy-to-read table format.
Regex Flags Support
Toggle g (global), i (case-insensitive), m (multiline), and s (dotall) flags for precise matching.
Instant Error Feedback
Invalid regex patterns show immediate error messages so you can fix syntax issues fast.
Cheat Sheet Reference
Quick reference for common regex patterns including email, phone, URL, and number matching.
100% Private & Secure
All regex testing happens in your browser using JavaScript RegExp. No data ever leaves your device.
Free Regex Tester Online — Test Regular Expressions
Our regex tester online tool lets you write and test regular expressions with instant visual feedback. See matches highlighted in real time as you type your pattern and test string. The match details table shows each match's text, starting index, and length — making this regex tester ideal for debugging patterns, validating form inputs, and learning regular expressions.
Regular Expression Tester — Flags & Capture Groups
Common Regex Patterns for Validation
Use this regex pattern matcher for email validation ([a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}), phone numbers (\d{3}-\d{3}-\d{4}), URLs (https?:\/\/[^\s]+), and more. Test any pattern with your own text to see exactly what matches and where.