i want to start designing some unique wordpress themes and would have the themes sponsored, but what can i use to encode the footer file? as a lot of people just remove the links?
Zend or Ioncube are the most secure (popular) ways of encoding, but require loaders to the installed on the server the script is being run.. so probably not practical just for a footer link. Look into base64 encoding which isn't anywhere near as secure but will be a deterrant for the average user. You would need to have a hook in the encoded code so it isn't just deleted.
As in you need some essential code within the encoded source so it isn't simply deleted. This can be done by calling a rogue variable from elsewhere in the code, or to the extreme contacting a remote server.