Answer by Josha Inglis for URL Validation function improving

This would be my attempt:

((?:http|https)://)?(?:www\\.)?[\\w\\d\\-_]+\\.\\w{2,3}(\\.\\w{2})?(/(?<=/)(?:[\\w\\d\\-./_]+)?)?

EDITAdded in a back-reference (?<=/)for extra specificity

EDIT 2Added optional search for country name in URL (eg www.google.com.in)