So, I decided to build my own. txtl tries to autodetect what mode you want based on the input, and in general is fast and gets out of your way as much as possible. For example, if you paste in a number then it will show base conversions, but if it looks like an epoch timestamp then it will display the corresponding date. And of course it's open source at https://github.com/viveksjain/txtl/
This was partly also a way for me to try using LLMs to build a frontend/new project. This could probably be a whole blog post, but I see why some people can say that LLMs can 10x their coding productivity (I certainly didn't find this true in my day job) - I was really impressed with what o1 can do, it probably got me 70% of the way there in one shot. And as someone not familiar with frontend development, iterating was way faster. But, it still requires plenty of feedback and requires handholding - I had to completely rewrite the diff rendering logic, no matter what I tried I couldn't get an LLM to get it right.
Would love feedback on the autodetection and overall usability!