My application [0] I used daily for 13 years stores the data in localStorage and I had several unpleasant data loss incidents - mostly me cleaning storage of the wrong browser tab. Thankfully, a simple JSON dump/import feature enables a good enough degree of reliability. Thanks to it, I didn't lose any data in 5 years, but now I have a questionable habit where I defensively export data before every major edit or deployment.

Simple localStorage replication has been an interest of mine for many years and I explore available solutions multiple times a year, but none of these ticks all the boxes - no server to maintain; free; optional for users; bring your own storage; the app stays a web page; cross-browser. I wish browsers had a file system API that allowed the app to read/write to specified directory or a file in background, which users may sync with their tool of choice, like Google Drive.

[0] https://github.com/Klaster1/timer-5

This made me think - is there a simple way to sync localStorage with my Firefox profile? If not, it doesn't sound like a WebExtension too difficult to create.

I actually implemented an export/restore function at one point and ended up taking it out.

I waffled heavily on that feature but in the end only losing the last recorded weight for each exercise didn’t feel like enough of a loss to warrant the cluttering up of the interface or reliance on external services.