Free Online Regex Tester Tool
Test, debug, and visualize regular expressions in real-time. Enter your regex pattern and test string, see matches highlighted instantly, and get a detailed explanation of your pattern. 100% client-side.
"2026-07-12"
"2026-07-11"
"2026-08-15"
"2026-13-01"
(?<year>\d{4})— Named capture group-— Literal "-"(?<month>\d{2})— Named capture group-— Literal "-"(?<day>\d{2})— Named capture groupJavaScript RegExp engine · 100% client-side
How to Use the Regex Tester Tool
Enter Your Pattern
Type your regular expression pattern in the regex input field. Add flags like g (global), i (case-insensitive), or m (multiline) as needed.
Add Test String
Enter the text you want to test against in the test string area. The tool instantly highlights all matches.
Review Results
See matched text highlighted, view capture groups, and read a plain-English explanation of what your regex does.
Powerful Regex Tester Features
Everything you need to test and debug regular expressions — all in one free tool.
Real-Time Matching
See matches highlighted instantly as you type your pattern or test string.
Match Highlighting
All matches are highlighted in the test string with visual distinction for capture groups.
Capture Groups
Displays all capture groups and their values for each match, including named groups.
Pattern Explanation
Get a plain-English breakdown of your regex pattern explaining what each part does.
Flags Support
Supports g (global), i (case-insensitive), m (multiline), s (dotall), u (unicode), y (sticky) flags.
Copy Results
Copy the regex pattern, test string, or match results to your clipboard.
Clear & Sample
Load a sample regex and test string to get started quickly.
100% Client-Side
All regex processing happens in your browser. Your data never leaves your device.
Why Use Our Regex Tester Tool
The fastest way to test and debug regular expressions. No sign-up, no data leaving your browser.
100% Free
No hidden fees, no usage limits. Test as many patterns as you need.
Privacy First
All regex evaluation happens in your browser. Your patterns never leave your device.
Instant Results
See matches and explanations update in real-time as you type.
Developer-Friendly
Perfect for debugging regex patterns, learning regular expressions, and validating input formats.
Key Highlights
- No sign-up required
- 100% browser-side processing
- Supports all common regex flags
- Capture group display
- Pattern explanation generator
- Works on any device
Frequently asked questions
What is a regular expression?
A regular expression (regex) is a sequence of characters that defines a search pattern. It's used for pattern matching, text validation, find-and-replace operations, and text extraction in almost all programming languages.
Is this regex tester really free?
Yes, completely free. No hidden charges, no usage limits.
Is my data secure?
Absolutely. All regex processing happens in your browser using JavaScript. Your patterns and test data are never sent to any server.
What regex flags are supported?
g (global - find all matches), i (case-insensitive), m (multiline - ^ and $ match line boundaries), s (dotall - . matches newlines), u (unicode), and y (sticky).
How do capture groups work?
Capture groups are defined with parentheses (...) in your regex pattern. Each group captures a portion of the match, displayed separately in the results. Named groups use the syntax (?<name>...).
What does the pattern explanation show?
The explanation breaks down your regex into individual components (character classes, quantifiers, anchors, groups) and describes what each part does in plain English.
Can I use this for learning regex?
Yes! The real-time highlighting and pattern explanation make this an excellent tool for learning regular expressions. See how changes to your pattern affect matches instantly.
Do I need to install anything?
No installation required. Works entirely in your web browser.
Can I use this on my phone?
Yes, fully responsive and works on all devices.