Regex Tester

Test regular expressions instantly. Enter a pattern, add flags and see matches highlighted in real time.

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What is a Regular Expression?

A regular expression (regex) is a sequence of characters that defines a search pattern. It is used for string matching, validation, and text manipulation in many programming languages.

How to test regex patterns

Enter your regex pattern and flags, then paste or type your test text. Click Run Test to see matches highlighted and listed below.

Common regex flags

  • g – global (find all matches)
  • i – case insensitive
  • m – multiline

Examples of regex patterns

Pattern: d+
Matches any sequence of digits

Pattern: ^[A-Za-z]+$
Matches a line with only letters

Pattern: (cat|dog)
Matches either "cat" or "dog"

Why developers use regex testers

Regex testers help developers quickly build, debug, and validate regular expressions for use in code, data validation, and text processing.