By using an open standard to store your data besides being as transparent as possible on the storage format which you can verify on your own using third party tools (we have a post about that https://outercorner.com/2016/08/01/storage_format.html) we also benefit for the scrutiny OpenPGP as been through.
We also wanted to make a simpler and safer option (and in our eyes, more pleasant to look at) to existing password managers.
We also wanted to make a simpler and safer option (and in our eyes, more pleasant to look at) to existing password managers.