A comma in a string should be encoded as %2C . It is recommended you use your platform's normal URL building libraries to automatically encode your URLs, to ensure the URLs are properly escaped for your platform.

URL encoding converts non-ASCII characters into a format that can be transmitted over the Internet. URL encoding replaces non-ASCII characters with a "%" followed by hexadecimal digits. URLs cannot contain spaces. URL encoding normally replaces a space with a plus (+) sign, or %20.

URL Encoding (Percent Encoding) URL encoding converts characters into a format that can be transmitted over the Internet. URLs can only be sent over the Internet using the ASCII character-set. Since URLs often contain characters outside the ASCII set, the URL has to be converted into a valid ASCII format.