PHP regex tester & explainer

Email address

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

URL (http/https)

/^https?:\/\/[^\s\/$.?#].[^\s]*$/

IPv4 address

/^(\d{1,3}\.){3}\d{1,3}$/

UK/US phone number

/^[\+]?[(]?[0-9]{3}[)]?[-\s\.]?[0-9]{3}[-\s\.]?[0-9]{4,6}$/

Date (YYYY-MM-DD)

/^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$/

Hex colour code

/^#?([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$/

Slug (URL-friendly)

/^[a-z0-9]+(?:-[a-z0-9]+)*$/

Postcode (UK)

/^[A-Z]{1,2}\d[A-Z\d]? ?\d[A-Z]{2}$/i

ZIP code (US)

/^\d{5}(-\d{4})?$/

Strong password

/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[\W_]).{8,}$/

Username (3-20 chars)

/^[a-zA-Z0-9_]{3,20}$/

HTML tag

/<([a-z][a-z0-9]*)\b[^>]*>(.*?)<\/\1>/i

IP address in text

/\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b/

Decimal number

/^-?\d+(\.\d+)?$/

Credit card (basic)

/^\d{4}[\s\-]?\d{4}[\s\-]?\d{4}[\s\-]?\d{4}$/