Regex Tester & Validator

What is a Regex Tester?

A regex tester is an essential debugging tool for testing and validating regular expressions (regex patterns) against sample text in real-time. Our regex tester helps developers, data analysts, and text processing specialists test pattern matching, debug regex syntax errors, view capture groups, and experiment with regex flags before implementing patterns in code. Whether you are validating email addresses, extracting data from logs, parsing URLs, searching text, or cleaning datasets, our tester provides instant feedback with match highlighting, group extraction, and detailed error messages. It supports all JavaScript regex flags (global, case-insensitive, multiline, dotAll, unicode, sticky) and includes a common patterns library for email, URL, phone, IPv4, dates, and hex colors. All testing happens client-side ensuring your sensitive regex patterns and test data remain completely private.

How to Use Our Regex Tester

1. Enter your regular expression pattern in the "Regular Expression" input field
2. Select regex flags you need: global (g), case-insensitive (i), multiline (m), etc.
3. Paste or type your test text in the "Test Text" textarea to match against
4. Click "Test Pattern" to execute the regex and see all matches instantly
5. Review matches displayed below showing match text, position index, and captured groups
6. Use "Quick Patterns" to load common regex patterns (email, URL, phone) for learning
7. Copy the working regex pattern to clipboard for use in your code
8. Adjust flags or pattern and re-test until you get desired matching behavior

Key Features & Benefits

Common Use Cases

Why Choose Our Regex Tester

• ✓Instant Testing: See matches immediately with no delays. Test and refine patterns in seconds.
• ✓All Flags Supported: Unlike basic testers, we support all 6 JavaScript regex flags for complete testing.
• ✓Match Details: View match text, index position, and capture groups for every match - essential for debugging.
• ✓Common Patterns: Pre-built patterns for email, URL, phone, and more. Learn by example and adapt to your needs.
• ✓Privacy Protected: Client-side processing means your regex patterns and test data never leave your browser.
• ✓100% Free: Unlimited pattern testing without registration, API limits, or premium features.
• ✓Error Messages: Clear validation errors help you fix broken patterns quickly instead of crashing your code.
• ✓Multiple Matches: Global flag shows all matches, not just the first. See complete matching behavior.
• ✓Group Extraction: View captured groups essential for data extraction and replacement patterns.
• ✓Developer Friendly: Built for developers with clean output, proper JavaScript regex support, and no quirks.

Frequently Asked Questions