How Discord Stores Billions of Messages - reasons and process moving from MongoDB to Cassandra. I appreciate the author talking about an error scenario which caught them by surprise.
Sir, Please Step Away from the ASR-33! - an article from 2010 talking about unicode and programming languages. While I do not agree with any of the major points the article makes, it is a nice thought experiment worth entertaining.
How does FaceTime Work? - FaceTime is IMHO the best VoIP service available right now and while there is some speculation included it is interesting to see how the serice works.
How Actors Work Internally in Swift - understanding the building blocks and when dealing with concurrency is essential and this is the best explanation for Swift Actors I have seen so far.
Email Authenticity 101: DKIM, DMARC, and SPF - there are not many hosting related things I am not willing to do, but hosting an email service is pretty far on top of the list. If I am ever forced to this post will be really handy.