Email Address
^[^\s@]+@[^\s@]+\.[^\s@]+$
Matches simple email format
URL (HTTP/HTTPS)
^https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)$
Matches HTTP and HTTPS URLs
Phone Number (US)
^(\+1[-.]?)?\(?\d{3}\)?[-.]?\d{3}[-.]?\d{4}$
Matches US phone numbers with various formats
Date (YYYY-MM-DD)
^\d{4}-\d{2}-\d{2}$
Matches ISO 8601 date format
Time (HH:MM:SS)
^([01]?[0-9]|2[0-3]):[0-5][0-9]:[0-5][0-9]$
Matches 24-hour time format
Hexadecimal Color
^#?([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$
Matches hex color codes (#RRGGBB or #RGB)
IP Address (IPv4)
^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$
Matches IPv4 addresses (0.0.0.0 - 255.255.255.255)
Credit Card
^\d{4}[\s-]?\d{4}[\s-]?\d{4}[\s-]?\d{4}$
Matches 16-digit credit card numbers
Username (alphanumeric + underscore)
^[a-zA-Z0-9_]{3,20}$
Matches usernames 3-20 chars, letters/numbers/underscore only
Slug (URL-friendly)
^[a-z0-9]+(?:-[a-z0-9]+)*$
Matches URL slugs (lowercase, hyphens, no spaces)
Hashtag
^#[a-zA-Z0-9_]{1,30}$
Matches Twitter/social hashtags
Whitespace Only
^\s*$
Matches empty string or whitespace only