I'm currently working on a tiny task management web application for my own needs. To minimize the implementation work I came up with a concept that I think could suit a number of applications like this as well:

- No user signup (no backend at all)

- Local first (via localstorage)

- Optional bring-you-own-storage functionality for sync and backup

The last point would allow the user to provide, say, an S3 endpoint and api key to allow the application to synchronize its state to a remote data store. By supplying the same credentials to the application on another device, one would have cross-device sync effectively for free. To avoid exposing data to the storage provider I'm also implementing client-side encryption.

Now the only remaining question is what storage protocol to use. I've found S3 client libraries to be severely lacking for browser environments (the AWS SDK is a mess and seems to rely on nodejs shims to work, not to mention its gargantuan size).

What are other easy to use and widely available storage protocols? WebDAV? A git repo? Curious to hear what else is out there!