At the company's Platform State of the Union talk at, an Apple executive showed the two main alternatives that developers can use for handling sign-on: Facebook and Google.
"We want to offer a better option," the Apple executive told thousands of developers at the conference. "It offers fast, easy sign-in without all the tracking."
The service opens a new challenge in the fraught area of user privacy. Tech giants are in agreement that privacy is a big deal, but Apple argues that free, ad-supported services from Google and Facebook compromise your privacy.
However, that position contrasts with a remark by Apple Chief Executive Tim Cook. "We're not really taking a shot at anybody," Cook said of the service in an interview with CBS News' Norah O'Donnell. (Editors' note: CNET is owned by CBS.)
But Brad Hill, a Facebook programmer working on logon technology, criticized Apple for its requirement that any app supporting third-party sign-on also support Sign In. Apple is "using its platform power to privilege its own offering, not setting neutral pro-privacy requirements," Hill tweeted Monday.
Facebook and Google didn't respond to a request for comment.
Apple: Why you should use our sign-in tech
The Sign In service lets developers rely on Apple when trying to get people to sign up for a new account. Apple verifies email addresses, offers dual-factor authentication, cracks down on fraud and gives developers an indication on whether users are authentic.
At their developer-focused shows in recent weeks, Facebook and Google each touted privacy as a top priority.
"Privacy cannot be a luxury good offered only to people who can afford to buy premium products and services," Google CEO Sundar Pichai said in a May op-ed. That stance contrasts with Apple's criticism that free services can turn your personal data into the product they sell to advertisers.
First published June 3, 6:16 p.m. PT.
Update, June 4, 8:40 a.m.: Adds comment from Facebook programmer.