RegEx Tester

What Are Regular Expressions?

Regular expressions (regex) are patterns used to match character combinations in strings. They are supported in virtually every programming language and are essential for text processing, input validation, search-and-replace, and log parsing.

JavaScript Regex Flags

• g — Global: find all matches, not just the first
• i — Case-insensitive matching
• m — Multiline: ^ and $ match line boundaries
• s — Dotall: . matches newline characters

Common Use Cases

• Validating email addresses, phone numbers, and URLs
• Extracting data from log files and structured text
• Search-and-replace in code editors and IDEs
• Building input masks and form validators
• Parsing and transforming CSV, JSON, and XML data