I was curious and tested that 401-byte JSON snippet that packs to 80 bytes, at the end of the article. It GZips to 227 bytes. Which isn’t as optimal as 80 bytes, sure, but it’s a heck of a lot less development work. And in a real-world scenario, with JSON files large enough for you to care about size, you’re gonna get a lot more bang for your buck.

So, really not a sensible thing to do in all but the most extremely bandwidth-sensitive scenarios, but a neat exercise.

Also, protobuf is almost certainly a better bet if you need binary packing, as opposed to rolling your own.