There isThank you for clarifying. nothing illegal about it. The app is sharing passwords to hotspots that is uploaded to them by users. It is important to note that users have to specifically share the password to the service, they don't just automatically share the password of any system you log into. Unless you specifically sign an agreement with someone saying not to share a password there is no reason that you cannot do so. Even then it is probably a civil dispute rather than a criminal one.
Think of it like this though - you go to a local public hotspot, and you get the password from the owner. Ten minutes later your friends join you and you give them the password, have you committed a crime? Same principal, just automated.
Now whether or not this is a secure method of sharing password is a different question. Whether it does or doesn't though does not make it illegal.
There is a similar app that I have greater faith in called
Instabridge that does basically the same thing.