Nothing special, but I didn't want to share my dietary habits with an unknown number of third parties, so I built my own calorie tracker. I didn't use anything fancy, I just ran Grist on my home server with a half dozen tables. Had to rewrite it a couple of times to support stuff like recipes, but it's good enough for my purposes. Didn't even need to add auth to it, I just use Tailscale on my personal devices to access the server from anywhere without exposing it to the internet.