Tracking return visits with The Anonymous Cookie

I’m still working through the pros and cons of using cookies.

On the one hand, they seem like they will allow some super-useful things at relatively low cost, such as tracking a returning visitor in order to show “visitors” and “unique visitors”.

But adding non-essential cookies (analytics are classed as non-essential) means that, in theory, if you’re in the EU you’re supposed to have informed, but not explicit consent for that cookie, which I read as: “you need a pop-up, but not a checkbox”.

A session cookie is, I believe, an “online identifier” and this is personally identifiable and subject to DPA or GDPR in the UK/EU (though I would argue that because you can’t perform a lookup on the session ID it’s not, but who am I to argue). So session cookies aren’t great for tracking (and wouldn’t scale). But nor is any other unique ID stored in a cookie and sent to the server.

There’s been a great conversation about this topic in a GitHub issue in Kownter’s competitor/collaborator  Fathom (I love them, it’s all good). And I’ve realised (yeah, took a while!) that you don’t need an ID in the cookie.  You can just set tracked_with_kownter = 1 or whatever, and that will identify a returning visitor to the site you’re tracking.

So the next step is: what can I put in the cookie that is anonymous, but useful?