Online Regex Tester & Debugger
Test, debug, and validate regular expressions in real-time with live match highlighting and group capture breakdowns.
Match Breakdown & Position Index (2)
| # | Match String | Index Range | Captured Groups |
|---|---|---|---|
| 1 | support@codifyui.com | [37, 57] | — |
| 2 | admin.user@company.co.uk | [69, 93] | — |
How to Use the Free Regex Debugger Online & Pattern Tester
Regular expressions (regex) are pattern-matching strings used by software engineers to validate user input, extract structural data, reformat code strings, and query log files. Our interactive online Regex Tester provides instant, real-time pattern matching with live visual highlights. To start testing, enter your regular expression pattern in the input box, configure search flags like global (g) or case-insensitive (i), and paste your sample text into the test area.
As you type, our client-side regex parser calculates exact match boundaries, highlights string occurrences in real-time, and breaks down individual capture groups into structured index tables. If your regular expression contains invalid syntax—such as unclosed parenthetical groups or misplaced quantifiers—our inspector highlights syntax errors immediately to assist fast debugging.
Essential Regular Expression Syntax Cheat Sheet
Any digit (0-9)
Word char (a-z, A-Z, 0-9, _)
Whitespace character
Character range match
Frequently Asked Questions
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