About Regex Tester

Test and validate regular expressions with real-time matching and detailed results. Essential for pattern matching, text validation, and data extraction. This tool helps you build and debug regex patterns with instant feedback.

Regex Syntax Guide

. (dot): Matches any single character except newline
* (asterisk): Matches 0 or more of the preceding character
+ (plus): Matches 1 or more of the preceding character
? (question): Matches 0 or 1 of the preceding character
[abc]: Character class - matches any one of a, b, or c
^: Start of string, $: End of string
\d: Digit, \w: Word character, \s: Whitespace

Frequently Asked Questions

What is a regular expression?

A regular expression (regex) is a sequence of characters that defines a search pattern. It's used for pattern matching, text validation, and data extraction from strings.

What do the flags mean?

Flags modify how the regex works: 'g' finds all matches (global), 'i' ignores case, 'm' treats ^ and $ as line boundaries (multiline), 's' makes . match newlines (dotall).

How do I match special characters literally?

Use backslash (\) to escape special characters. For example, to match a literal dot, use \. instead of just . which matches any character.

What are common regex mistakes?

Common mistakes include forgetting to escape special characters, not using anchors (^ and $) for exact matches, and creating overly complex patterns when simpler ones would work.