A very simple tool for converting weight.
I wrote this back in early 2017 when I was using Weight Watchers to diet and their website only worked in stones and pounds when recording weight, and yet was happy to use metric for food weights, etc. On top of that I'd been recording my weight in Google Fit for some time up until that point and I was using kilos there.
So, every time I went to put my weight into the WW website, I had to use some crappy conversion site that was filled with adverts and the like.
On top of that, I couldn't persuade Google to do the conversion for me because the WW site wanted stones and decimal pounds, not decimal stones, etc.
So, eventually, I cracked and knocked together a very quick and dirty conversion tool. Designed for me to easily find on my phone, and 100% hosted on GitHub (because... reasons).
https://blog.davep.org/weight/ was the result. It got written, never needed to be tweaked again, isn't anything too clever (and has a couple of little edge case annoyances and is written in a way I probably wouldn't write it now) but at least the itch was scratched and I didn't have to and still don't have to use rubbish advert-filled sites.