A clever developer has wrapped up the web interface for WhatsApp into a pretty neat Mac App. So if you have an Android phone and want to use WhatsApp on your Mac, have a look on GitHub for the Zip download, unzip it and you’re good to go.
WhatsApp doesn’t normally like people fiddling with their API however this uses the same API they use for their Web Client. That is good news because I don’t see how they could easily shut this down.
The source code is also provided so you don’t have to worry about them stealing your details or messages. That is always a bonus in this day and age.