Regular Expression Tester

What is Regular Expression?

A regular expression (often shortened to "regex" or "regexp") is a powerful tool for pattern matching and text manipulation. Regular expressions provide a concise and flexible way to match strings of text, such as particular characters, words, or patterns of characters.

Regular expressions are supported in most programming languages including JavaScript, Python, Java, PHP, Ruby, and more. They're essential for tasks like:

• Validation: Check if user input matches expected formats (email, phone, etc.)
• Searching: Find specific patterns within large text bodies
• Extraction: Pull out specific data from strings
• Replacement: Find and replace text based on patterns
• Splitting: Break strings into parts based on delimiters

How to Use This Tool

1. Enter Your Pattern: Type or paste your regex pattern in the pattern field. You can also load a common pattern from the dropdown menu to get started.
2. Select Flags: Choose the appropriate flags for your use case. The most common are g (global - find all matches) and i (case-insensitive).
3. Add Test Text: Enter or paste text you want to test your pattern against. The tool will automatically highlight all matches.
4. Review Matches: See all matches highlighted in yellow, with detailed results showing the match text, position, and capture groups.
5. Test Replacements: Optionally enter a replacement value to preview how your text will change when matches are replaced.

Common Regex Patterns