Open-source. Encrypted if you want. Synchronized using WebDAV (also Dropbox, NextCloud and OneDrive). Uses markdown. Has tags. And apps for everything (Windows/macOS/Linux/Android/iOS/terminal).
I use Zettlr as a markdown editor, with the underlying directory being in git. It's not encrypted, though doing that should be pretty easy with something like EncFS.
I'm curious if there is something you are using on mobile for vimwiki? I've been using termux on Android, which works well enough.
My backup method is pretty simple but it’s been silently chugging along for months now without a single hiccup. It’s just a git commit via cron job: https://thelinell.com/using-vimwiki/
What I eventually ended up doing was moving to vscode. I use it my main IDE for the last couple years. I have a linux vm running for all my development, with vscode remote ssh.
- I keep a folder for each month - I have a file in each month called YYYYMM-dailies.md, level 2 headings for each day - Notes that grow too complex for the "dailies" get their own file in the folder. A number of these might get polished and copied into a document site somewhere. - Sometimes I'll make a subdirectory of "snips" with small scripts or pseudo-scripts (stuff to copy/paste) - The integrated shell lets me paste commands into my dev vm and copy the results back into my notes.
A feature of this is that while it's not really "synchronized", I can vscode-remote-ssh from multiple machines, or just ssh into the vm to get my notes. You can use rclone or keybase+rsync to backup the notes directory (or keybase's git if you want to check notes in).
Another
A HN search illustrates the amount of markdown note apps available: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
The number of times this has saved me time figuring out "Oh .. i saw that error before .. how did I fix it?" and "who did i talk to about X and what did they say" months to years later has proven to be super helpful and I will be continuing indefinitely.