This is something I worry about all the time as well, especially since I’ve started to learn how to code and experienced how easy it is to mess up and send a list with all registered users to everyone opening a page. (This was in a test environment.)
As a user, there is no proper way I know of to verify an app’s security. Most apps are closed source, but even if you could view the code, what would you look for?
Both Apple and Google have a verification process for apps that are published in their app stores, but if these worked, we wouldn’t see this happening.
There are academic researchers working on apps and privacy as well, but it’s not like you can ask them for a report on an app you’re thinking of installing.
I think it basically comes down to trust. Check if a developer has messed up in the past and how they dealt with that, that sort of stuff. And for dating apps there is this interesting article: https://www.privacyguides.org/articles/2025/06/24/queer-dating-apps-beware-who-you-trust/#reducing-the-risks-when-using-dating-apps
It’s a long read (haven’t fully read it myself yet) and it paints a bleak picture, but that’s the world we live in today.
Thanks, that’s good to know! If I do ever decide to release an app, I’ll definitely look into this.