Have you ever been on a website that asks you to login using Facebook? This usually appears as a quick one-click button that lets you link this app to Facebook so you don’t have to manually enter a lot of your own information into the new website. So how do websites get this button on their website?
It’s surprisingly easy. Take a look at the Facebook Login Overview on Facebook for Developers. Any website can use the Login if they only need access to a user’s public profile and email address. The overview states that “to ask for any other permission, your app will need to be reviewed by Facebook before these permission become visible in the Login Dialog to the public who’re logging into your app with Facebook”.
Looking at their App Review process, apps have to submit a request on a feature by feature basis and match that request to the product offered on their site. Businesses also need to verify their business identity. Businesses also have to sign a usage agreement.
That is somewhat reassuring, but let’s rewind a bit here. Any business, verified or unverified can use this Login feature to gain access to the public profile. Think about what’s on your public profile: a cover photo, gender, networks, schools attended, age range, language, country, and any information that appears on public searches. Imagine what companies can do with some of this information.
Some of these third-party websites may also sync up with Facebook to post some of the information from their app on your profile’s timeline. For example, Goodreads is a very popular website among librarians. Depending on how you set up your Goodreads account, you may have given Goodreads permission to automatically post your completed books to your timeline. Do you want all of your Facebook friends to know everything you read?
If you’ve already accidentally synced an app with your Facebook profile, there are usually ways to undo or change the settings. Here’s Goodread’s Help page if you want to take a look at the permission shared between Goodreads and Facebook. They also provide information about how to adjust the settings.