Nothing
As of now I’ve downloaded the app and given very valuable security collateral information and received nothing in return, not even a verification code to access the app.
Not enough ratings yet to assess Signings.io.
Signings.io appears legitimate, with a few gaps. AppsHunter Legitimacy Score for Signings.io is 68/100.
Based on 68 of 100 points across 7 verification signals from App Store and developer data.