Online Regex Tester

Test, debug, and refine your regular expressions against sample text in real-time.

What is a Regular Expression (Regex)?

A **Regular Expression (Regex)** is a sequence of characters that forms a search pattern. It can be used for string matching, searching, and replacing text within larger data sets. Regex is a standard feature in almost all programming languages, including JavaScript, PHP, Python, and Java.

Common Regex Flags

  • g (Global): Don't return after the first match, find all occurrences.
  • i (Case-insensitive): Ignore case differences during matching.
  • m (Multi-line): Treat start (^) and end ($) characters as working across multiple lines.

Why use an Online Regex Tester?

Regex patterns can become complex and difficult to read. Our **Online Regex Debugger** allows you to test your patterns against real data without having to run your full application, helping you find errors and edge cases in seconds.

Regex Cheat Sheet for Developers

Character Classes
\d : Digit [0-9]
\w : Word character [A-z0-9_]
\s : Whitespace character
Quantifiers
+ : 1 or more
* : 0 or more
? : 0 or 1
{n} : Exactly n times
Anchors
^ : Start of string
$ : End of string
\b : Word boundary