Regex Tester
Test and debug regular expressions with real-time pattern matching
Enter a pattern and test string
to see results here
Common Examples
Quick Reference
What is a Regular Expression?
A regular expression (regex or regexp) is a sequence of characters that defines a search pattern. It's used for pattern matching within strings, allowing you to search, match, and manipulate text based on specific patterns rather than exact matches.
Regular expressions are widely used in programming, text editors, and command-line tools for tasks like data validation, text searching, find-and-replace operations, and text parsing. They provide a powerful and flexible way to work with text data.
Common Use Cases for Regex
Data Validation
Validate email addresses, phone numbers, URLs, credit card numbers, and other formatted data
Text Search & Extract
Find specific patterns in large text documents, extract data from logs, or parse structured text
Find & Replace
Perform complex search-and-replace operations across files with pattern-based transformations
Data Parsing
Extract structured data from HTML, CSV, JSON, or other formatted text sources
Understanding Regex Flags
Global (g)
Find all matches in the text rather than stopping after the first match. Essential for finding multiple occurrences of a pattern.
Case Insensitive (i)
Make the pattern match regardless of case. For example, /hello/i will match "Hello", "HELLO", and "hello".
Multiline (m)
Treat ^ and $ as matching the start and end of each line, not just the entire string. Useful for processing multi-line text.
Frequently Asked Questions
What is the difference between encodeURI and encodeURIComponent?
encodeURI is for encoding a complete URL and preserves special URI characters like :, /, ?, and &. encodeURIComponent is for encoding URI components (like query parameters) and encodes all special characters except letters, digits, and a few symbols.
Are regular expressions case-sensitive?
By default, yes. Regular expressions are case-sensitive unless you use the case-insensitive flag (i). With the i flag enabled, your pattern will match both uppercase and lowercase letters.
How do I escape special characters in regex?
Use a backslash (\) before special characters like . * + ? ^ $ &lbsp; &rbsp; [ ] ( ) | \. For example, to match a literal period, use \. instead of just .
Is my data safe when using this tool?
Absolutely! All regex testing happens locally in your browser using JavaScript. No data is sent to any server, ensuring your complete privacy and security.