{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "URL",
  "description": "A standard URL",
  "type": "string",
  "pattern": "^(ftp:\/\/|http:\/\/|https:\/\/)?([A-Za-z0-9_]+:{0,1}[A-Za-z0-9_]*@)?(^([ \t\r\n\f])+)(:[0-9]+)?(\/|\/([[A-Za-z0-9_]#!:.?+=&%@!-\/]))?$"
}