What is a good regular expression to match a URL? [duplicate]

Regex if you want to ensure URL starts with HTTP/HTTPS:

https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)

If you do not require HTTP protocol:

[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)

To try this out see http://regexr.com?37i6s, or for a version which is less restrictive http://regexr.com/3e6m0.

Example JavaScript implementation:

var expression = /[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)?/gi;var regex = new RegExp(expression);var t = 'www.google.com';if (t.match(regex)) {  alert("Successful match");} else {  alert("No match");}