Hi Matthieu!
I guess I decided to write my own tool for different reasons. I had checked other libraries before but none of them seem to be exactly what I was looking for (be it because of looks, API, available charts, whatever). To be completely honest, I also felt what I needed was pretty simple and decided to write it myself and learn a bit about SVG along the way. After that, I was really happy with the results and decided to share it as a library. There was a similar question in the
reddit post if you want to look at it.
I hadn't heard about these particular libraries until after publishing Charty, and I believe they look really good. I am going to add some more features to Charty because my original use case justifies them, and was planning to do further work on it only as long as community reception demands it, since it makes no sense to write code that no one will use :-)
Thanks for writing!
Juan.