in reply to Using Perl to access notes/memos on my mobile

For text-only, you could also store the notes in localStorage (or even localForage) and use (say) Server-Sent Events to reconnect from the web page to the server automatically and synchronize the notes.

The harder part of this would be to wrap the HTML page in an "app" that can also run and synchronize in the background without needing the browser open.

Personally, I've used an IMAP server together with the K9 mail application for storing notes. It's a simple protocol that knows how to deal with network interruptions.