Regular Expression Tester

Test and validate your regular expressions in real-time. Enter a pattern and test string to see matches, capture groups, and match positions. Use the flags to modify the matching behavior.

Basic Examples

Phone Number (US Format)

Pattern:

$\d{3}$ \d{3}-\d{4}

Test with:

(555) 123-4567

Email Address

Pattern:

[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}

Test with:

user@example.com

Capture Groups

Date Parsing

Pattern:

(\d{4})-(\d{2})-(\d{2})

Test with:

2024-03-15

This will capture year, month, and day in separate groups.

URL Parsing

Pattern:

(https?):\/\/([^\/]+)(\/[^\s]*)?

Test with:

https://example.com/path/to/page

This will capture protocol, domain, and path in separate groups.

Common Flags

Global (g)

Find all matches in the text, not just the first one.

Example with 'g' flag:

\b\w+\b Test: The quick brown fox

Case Insensitive (i)

Match letters regardless of their case.

Example with 'i' flag:

hello Test: Hello HELLO hello

Multiline (m)

Treat each line as a separate string for ^ and $ anchors.

Example with 'm' flag:

^\d+

Test: 
123
456
789

Tips & Best Practices

Use \b for word boundaries
Use \d for digits instead of [0-9]
Use \w for word characters (letters, digits, underscore)
Use \s for whitespace characters
Use ^ and $ to match start and end of string
Use (?:...) for non-capturing groups
Use \ to escape special characters
When copying patterns, use single backslashes (e.g. \d4), not double