Arguably, encryption is Stingle Photos’ most important feature. Although the app uploads your photos to Stingle’s cloud service, the service’s operators can’t look at your photos. That’s because the app, which runs on your phone or tablet, encrypts them securely using Sodium cryptography.
Since the photos are encrypted before ever leaving your phone—using a key that isn’t ever available to Stingle’s operators—you’re safe from attackers getting a photo dump from Stingle’s cloud. You’re also safe from Stingle’s own operators pulling a LOVEINT on you or getting socially engineered by someone with a believable voice begging to get your photos back… More here.
I suspect that photo storing apps are a hard sell at this time thanks to previous service closures and the fact that too many of us have so many photos stored that they can tend to lose their importance.
Personally, I would be much more likely to stick my photos on a local drive as a backup than another online service aside from iCloud. That feels like a more financially sensible and safer long term solution.