https://currenttimeutc.com/
It's a minimalist time zone converter. The real value add, in my opinion, is that it lets you look up multiple locations and add them all to list that updates in real-time. I built this a few years ago but I made a bunch of UX and quality of life changes recently. I have metrics around usage but I would be curious to chat with some users to get their take on how it can be improved.