Gegenfeld

Regex Tester

Test, debug, and understand regular expressions in real-time. Input your pattern, flags, and test string to see matches instantly highlighted.

//g
Flags:
9 matches found
The quick brown fox jumps over the lazy dog.
Character Classes
. Any character
\d Digit
\w Word char
\s Whitespace
Anchors
^ Start
$ End
\b Word boundary
Quantifiers
* 0 or more
+ 1 or more
? Optional
{3} Exactly 3
Sponsored

Powered by ManyPI

Turn any website into a type-safe API. Reliable, fast, and easy to integrate.

Learn more

What is a Regular Expression?

A Regular Expression (or Regex) is a sequence of characters that forms a search pattern. It can be used for string matching, text replacement, and data validation (e.g., checking if an email is valid).

Regex is supported in almost every programming language, including JavaScript, Python, PHP, Java, and Go. While the syntax varies slightly between engines, the core concepts remain consistent.

Common Flags

  • g (Global): Find all matches rather than stopping after the first match.
  • i (Case Insensitive): Matches will be case-insensitive (e.g., 'a' matches 'A').
  • m (Multiline): The start (^) and end ($) anchors match the start and end of *lines*, not just the string.

FAQ