Regex Tester

What Are Regular Expressions?

Regular expressions (regex) are patterns used to match character combinations in strings. They are used across every programming language for text search, validation, extraction, and replacement. Mastering regex lets you process text data efficiently and build robust input validation for web forms, APIs, and data pipelines.

Regex Flags Explained

• g (Global) — Find all matches in the string, not just the first.
• i (Case Insensitive) — Ignore uppercase/lowercase differences.
• m (Multiline) — Let ^ and $ match the start and end of each line.
• s (DotAll) — Let . match newline characters.
• u (Unicode) — Enable full Unicode matching and proper surrogate pair handling.