As CNET points out, Whitfield was able to make this online version, as Cards Against Humanity is offered for free via a Creative Commons license. (This is also why you can download a PDF of all the cards from the Cards Against Humanity website to make your own decks. Only buying the physical decks costs money.)
Cards Against Originality comes with the original deck of cards as well as all five expansion packs and the rules are the same. But playing it can be a bit of a challenge as it’s not really the type of game you can play against a computer. Someone needs to create a game and then send out a custom link to other people so they can join in. So you need to be able to get a group of people to play at the same time, which might be a little difficult if you want to play sporadically while at work.