The topic of open source video editors has come up a couple of times recently on HN [0] [1]. As I've commented in these threads, I used to be a big fan of Kdenlive, but after trying Davinci Resolve [2] (free as in beer), I don't see myself going back to any of the non-professional editors.
I've recently finished editing a couple of feature films [3] [4] using Resolve, so I went back to an unfinished project I had on Kdenlive. Turns out there's no way to export from Kdenlive to anything Resolve can import, so I wrote a quick and dirty importer over the weekend.
I realise it's pretty niche, but I've decided to release it as open source (GPLv3) anyway: https://github.com/ggambetta/mlt2fcp
[0] https://news.ycombinator.com/item?id=19725823
[1] https://news.ycombinator.com/item?id=19337689
[2] https://www.blackmagicdesign.com/products/davinciresolve/