What is a regular expression (regex)?

A regular expression (regex) is a sequence of characters that defines a search pattern. Regex is used for pattern matching within strings, allowing you to find, replace, or validate text based on specific rules. For example, you can use regex to find all email addresses in text or validate phone number formats. Validate emails with our Email Validator .

What do common regex symbols mean?

. matches any character, * matches 0 or more repetitions, + matches 1 or more repetitions, ? matches 0 or 1 occurrence, ^ matches start of string, $ matches end of string, [abc] matches any character in brackets, \d matches digits, \w matches word characters, and \s matches whitespace.

How do I test if my regex pattern works?

Enter your regex pattern in the pattern field and your test text in the text area. The tool will highlight all matches in real-time. You can see the number of matches found and extract specific groups. Use the case-sensitive and global flags to control matching behavior. Test against JSON data for API validation.

What are regex flags (i, g, m)?

i = case insensitive (A and a are treated the same), g = global (find all matches, not just first), m = multiline (^ and $ match start/end of each line). You can combine flags like "gi" for global case-insensitive matching.

Can I use this to learn regex?

Yes! This tool provides instant visual feedback showing which parts of your text match your pattern. Experiment with different patterns, see real-time results, and use the quick reference guide to learn regex syntax interactively. Parse URLs with our URL Parser using regex patterns.

Regex

Test patterns, Extract matches. Fast, secure, and works offline.

Regex Pattern

Pattern

global

ignore case

multiline

dotall

unicode

Test String

Quick Reference

digit [0-9]

word char

whitespace

any char

1 or more

0 or more

0 or 1

start/end

Frequently Asked Questions

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Diff

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Regex

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