: Facebook does not provide third-party developers with access to private user data or locked profile content. Security Risks
If the user ever used that profile picture on a public forum (Twitter, Reddit, LinkedIn), you can download their public (non-private) avatar via Google Images or Yandex. This does not work for private Facebook images. facebook private profile picture viewer online
They may ask you to log in with your own Facebook credentials to "authenticate" the search. In reality, they are stealing your username and password. : Facebook does not provide third-party developers with