Regex Tester Online Free — Test Regular Expressions with Match Highlighting | DevToolBox

Free online regex tester and debugger. Test regular expressions in real-time with match highlighting and capture groups. Supports JavaScript, Python, Go, and Perl patterns.

Regular Expression

//g

Global (g)Case insensitive (i)Multiline (m)Dotall (s)

Test String

About Regular Expressions

Regular expressions (regex) are powerful patterns used for matching, searching, and replacing text. They're essential for input validation, text processing, and data extraction. This tool tests your regex in real-time with JavaScript's regex engine.

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How to Use

Enter your regex pattern in the pattern field
Add flags (g for global, i for case-insensitive, m for multiline)
Type or paste your test text
View highlighted matches and match details in real-time

Common Use Cases

Validating email addresses, URLs, or phone numbers
Extracting data from text (log parsing, web scraping)
Search and replace operations
Input validation in web forms

Frequently Asked Questions

What is a regular expression?

A regular expression (regex) is a pattern used to match, search, and manipulate text. It's supported in virtually every programming language.

How do I test my regex?

Enter your regex pattern in the pattern field, add test text below, and the tool will highlight all matches in real-time. Flags like 'g' (global) and 'i' (case-insensitive) are supported.

Is my regex data safe?

Yes. All regex processing happens in your browser using JavaScript's built-in RegExp engine. No data is sent anywhere.