OMG!
So Pinpics got hacked a few years ago and a bunch of accounts got super messed up in the process. They have new owners, and the site is now stable again... However, a bunch of us had concerns and thus the migration to Pin & Pop. Not only for the data and the inventory interface but their trading platform is also superior. You can only trade ~ one weekend per month, and only for pins people list on "tables" but you can walk away with a few trades up to 100+ trades. Mail them off in one box, with one shipping, where they get authenticated and checked for issues, and then mailed back to you in 1-2 packages depending on how fast the inspection went. Without the years that Pinpics has behind them, there are still several thousand pins missing, especially on older, rarer stuff. But it's getting there!
There is also another major database called My Pin Central. This one was created because the person wanted to compete with Pinpics but they have issues on their own with data reliability. Looks like they use AI and robots to cull for new data and info and it's not always great.