1. Open Source
2. Notes must be encrypted when saved to the database.
3. Export options(markdown, or PDF or even txt files work, although that will mean no image support).
4. Lightweight, so I can either run it on a Raspberry Pi or a 1 GB VPS.
5. I would also like a web interface so that I can connect to it from any device.
I would also love to hear what applications you guys are using.