Regex Tester & Debugger

Test and debug regular expressions with real-time feedback and pattern library

Regular Expression

Standby

Source Material

Chars: 0
Lines: 0

Syntactical Atlas

A curated directory of regex primitives.

.Any char except newline
\dDigit (0-9)
\wWord char (a-z, A-Z, 0-9, _)
\sWhitespace
\DNon-digit
\WNon-word char
\SNon-whitespace
[abc]Any of a, b, or c
[^abc]Not a, b, or c
*0 or more
+1 or more
?0 or 1
^Start of string/line
$End of string/line
()Capturing group
|OR operator

Engine Parameters

Template Library

Email Address
\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b
Phone Number (US)
\(?\d{3}\)?[-.]?\d{3}[-.]?\d{4}
URL
https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)
IPv4 Address
\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b
Date (MM/DD/YYYY)
\b(0?[1-9]|1[0-2])\/(0?[1-9]|[12][0-9]|3[01])\/(19|20)\d{2}\b
Hex Color
#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})\b

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Frequently Asked Questions

What is a regex tester used for?

A regex tester is used to test and debug regular expression patterns before using them in code. It allows you to verify that your pattern matches the intended text, visualize matches, debug errors, and understand capture groups. This tool provides real-time feedback, highlighting matches as you type, making it essential for developers working with pattern matching, data validation, and text extraction.

How do I test a regular expression?

To test a regular expression: 1) Enter your regex pattern in the pattern field, 2) Paste or type your test text, 3) Configure flags (case-insensitive, global, multiline), 4) View real-time matches highlighted in the results. The tool shows match positions, capture groups, and the total number of matches. You can also upload text files for testing and export results.

What are regex flags and how do I use them?

Regex flags modify pattern matching behavior. The 'i' flag (case-insensitive) ignores letter case in matches. The 'g' flag (global) finds all matches instead of just the first one. The 'm' flag (multiline) makes ^ and $ match line starts/ends instead of string starts/ends. Simply check or uncheck the flag options in the tool to enable them.

How do capture groups work in regex?

Capture groups use parentheses ( ) to extract specific parts of a match. For example, in the pattern '(\d{3})-(\d{2})-(\d{4})' for a SSN, each set of parentheses captures a portion. Our tool displays all capture groups for each match, showing you exactly what each group extracted. This is useful for parsing structured data and extracting specific information.

Is my data safe when using this regex tester?

Yes! All regex testing happens entirely in your browser using JavaScript. Your patterns and test text are never uploaded to our servers or transmitted anywhere. The tool works completely offline after loading, ensuring your sensitive data remains private and secure on your device.