In recent years, the company has successfully encouraged a growing number of third-party app makers to allow users to log in with their Facebook identity rather than, say, by entering an email address or creating a dedicated account.
The result has been an influx of valuable data for the world's No. 1 social network, but concerns have also mounted about third-party developers gaining access to private information.
Chief Executive Mark Zuckerberg said at Facebook's developer conference in San Francisco that a new version of Facebook's log-in tool, called "log in anonymously," would let users control what information they allow third-party apps to see. He told developers the tool would let users feel more comfortable about logging into apps using Facebook.