- "No knowledge" (e.g. decrypted on the client) data storage. Very very difficult to do well.
- Make it easy for people to host data independently of you. Either by running your app on thier server (related to discussion above about for Heroku/Sandstorm, but a regular VPS is probably preferable), or using your client to read data stored in some generic format, e.g. an existing CardDav server, or even just Dropbox, with the web UI running locally, or as an extension.
The most important features for self hosting are probably maturity and stability, and signed releases via an up-to-date PPA.
For using some generic back-end you'd need to support it.
- Make it easy for people to host data independently of you. Either by running your app on thier server (related to discussion above about for Heroku/Sandstorm, but a regular VPS is probably preferable), or using your client to read data stored in some generic format, e.g. an existing CardDav server, or even just Dropbox, with the web UI running locally, or as an extension.
The most important features for self hosting are probably maturity and stability, and signed releases via an up-to-date PPA.
For using some generic back-end you'd need to support it.