Developer Tool

Regex Tester

Test and debug regular expressions live with real-time match highlighting and group capture.

Regular Expression Pattern

g Global i Case Insensitive m Multiline

Quick Insert Patterns

Test String

0 matches

Match Results

Enter a pattern and test string to see matches.

About This Tool

Regex Tester

Test and debug regular expressions against sample text in real time — with match highlighting and group capture display.

Why Use This Tool?

Test regex patterns before using them in production code
Debug complex regular expressions with live match highlighting
Learn regex syntax by experimenting with patterns interactively
Validate email, phone, URL, or date formats using custom regex
Used by developers, data engineers, and QA professionals daily

Overview

Regular expressions (regex) are one of the most powerful — and most misunderstood — tools in programming. A regular expression is a sequence of characters that defines a search pattern, allowing you to match, extract, validate, and transform text with incredible precision. Whether you are validating email addresses, extracting phone numbers from a document, parsing log files, or building a search-and-replace system, regex is the tool for the job. But writing regex is notoriously tricky — patterns can be difficult to read, subtle errors produce unexpected matches, and testing against sample data is essential. Our Regex Tester provides a live testing environment where you type your pattern and instantly see all matches highlighted in your test text. Captured groups are displayed separately, making it easy to understand exactly what your regex is extracting. Supports all standard JavaScript regex flags: global (g), case-insensitive (i), multiline (m), and dotAll (s).

How to Use

1

Enter Your Regex Pattern

Type your regular expression in the pattern field (without the surrounding slashes). Example: \d{10} for a 10-digit number.
2

Set Flags

Enable flags as needed: g (global — find all matches), i (case-insensitive), m (multiline — ^ and $ match line boundaries).
3

Paste Your Test Text

Enter or paste the sample text you want to test your pattern against in the test area.
4

See Matches Highlighted

All matches are highlighted instantly in the test text. The match count and positions are displayed.
5

Review Capture Groups

If your regex has groups (parentheses), the content of each captured group is shown separately below the matches.

Frequently Asked Questions

What is the difference between .* and .+?

.* matches zero or more of any character. .+ matches one or more (at least one character required). Use .+ when you need at least one match.

How do I match a literal dot in regex?

A bare dot (.) matches any character. To match a literal period, escape it with a backslash: \. Example: \d+\.\d+ matches a decimal number like 3.14.

What is a capture group?

Parentheses ( ) in a regex define capture groups. Whatever matches inside the parentheses is captured separately. Use them to extract specific parts of a match.

How do I test if an email address is valid with regex?

A basic email pattern: ^[\w.-]+@[\w.-]+\.[a-zA-Z]{2,}$. Paste it as the pattern and enter email addresses to test. (Full RFC 5322 email validation requires much more complex regex.)

What does the "g" flag do?

The global flag (g) finds ALL matches in the text. Without it, the regex stops after the first match. Almost always use "g" when you want to find every occurrence.