I've been dying for an open-source replacement for Evernote and I've been looking for an opportunity to learn Xamarin so I'm willing to contribute this if you're interested.
But isn't Xamarin.Forms only for mobile platforms? I can't find any information about building desktop apps with it (but also my only experience with Xamarin is currently MonoGame).
I'm totally a beginner with Xamarin and Gtk# but I'd be willing to give this a shot. I really like how multiple backends are supported via plugins in AlephNote.
You are more than welcome to contribute, especially because I'm also completely unexperienced with GTK# :)
Similar apps choke pretty hard on large collections of notes (1,000+)
My max. test case is around 100 notes. I honestly don't know how that many notes would perform, because all notes are always loaded.
If there is demand I could look into only lazy loading the actual note content and probabl other tweaks for big collections.
For the last few weeks I made my own notes client (mainly for [simplenote](https://simplenote.com/)) because the standard Electrum client felt pretty ... heavy.
Multiple backends are supported via plugins. Currently you can use it to access your notes on simplenote, Standard Note, Nectcloud/owncloud or no remote (aka local only).
I plan on adding Evernote support (only for plain, unformatted notes) and a better editor with a little bit of markdown highlighting (similiar to [qownnotes](http://www.qownnotes.org))
Tell me what you think and if you have ideas/criticism :D