Sign In with Apple and What It Requires From Your App

Sign in with Apple is a privacy-focused authentication system. It lets users log in to an app with their Apple Account, instead of an email and password or a service like Google or Facebook. Apple introduced it in 2019 and made it mandatory for apps with social login in 2020.

Today, if your app offers any third-party or social login option, App Store Review Guideline 4.8 requires you to offer a privacy-focused equivalent alongside it, and Sign in with Apple is the standard way to meet that rule. Many teams only find out it applies to them when a submission is rejected.

Why the Sign in with Apple Requirement Matters

Apple built Sign in with Apple as a direct response to a specific problem. Social logins from Google, Facebook, and others were collecting user data and metadata for ad targeting, often without users fully understanding what they'd agreed to. Facebook's 2019 FTC settlement, a $5 billion fine over privacy violations, became the clearest public example of what that data practice could cost a company.

Missing the requirement gets expensive once App Review gets involved. A new app with social login and no equivalent option can be rejected outright under Guideline 4.8, and an existing app that adds Google or Facebook login without one will have that update rejected. That means a delayed launch, or an urgent fix stuck in review behind a login feature you didn't plan for.

Apple says App Review typically handles 90% of submissions in under 48 hours, but every rejection sends you back into the queue. A fix that doesn't fully satisfy the reviewer's interpretation of Guideline 4.8 triggers another round. Enabling the capability takes minutes; the backend work described below is what takes time, and it's far cheaper to plan at the start than after a rejection.

Who Needs Sign in with Apple, and Who Doesn't

The Sign in with Apple requirement doesn't apply the same way to every app, and misreading your own situation is how teams end up building more than they need. Most of the confusion here clears up once you know which of these three situations describes yours:

• Building a new app with any social login. If your app includes signing up with Google, Facebook, or other third-party services, Sign in with Apple must be in the initial build. Adding it later often means reworking your auth flow under launch-week pressure.

• Running an existing app with third-party login already live. Apple's deadline for existing apps passed on June 30, 2020, and every update you submit is reviewed against the current Guideline 4.8. Add Sign in with Apple as an equal option alongside existing choices, and plan how users who signed up one way can switch to or link another.

• Running an app with no third-party login at all. If your app only uses its own email-and-password accounts, Guideline 4.8 doesn't apply. You can still add Sign in with Apple as a faster sign-up option, but that's a product decision, not a compliance one.

Guideline 4.8 also exempts a few specific cases: education and enterprise apps that require an existing institutional account, apps that use government or industry-backed electronic ID, and clients for a specific third-party service, such as an email app, where users sign in to that service to reach their content.

Everything that follows assumes you've placed yourself in one of these three, whether you're building natively, in React Native, or with another cross-platform framework.

How Sign in with Apple Works

The mechanism is built around minimizing what data ever leaves Apple's systems in the first place. When a user signs in, Apple verifies their identity and, on the user's very first authorization, passes your app only their name and email address. That detail trips up a lot of implementations: Apple does not resend the name and email on subsequent logins. Your backend needs to store that data as soon as it arrives.

Users also get to choose whether you see their real email at all. If they select Apple's private relay option, Apple generates a random forwarding address. Your emails reach the user through it only if you've registered your sending domains with Apple and authenticated them with SPF or DKIM; anything else bounces. Two-factor authentication and on-device Face ID or Touch ID confirmation round out the flow, the same layered-security thinking that applies to mobile app security generally. The whole design points to one goal: authenticate the user while exposing as little data as possible.

Implementing Sign in with Apple Across iOS, React Native, and Web

Three platforms need dedicated implementation work, and the same backend rules apply to all of them regardless of which you build for.

• iOS. Apple's AuthenticationServices framework provides the native Sign in with Apple button and authorization flow, making it the mature, first-party approach aligned with Apple's guidelines.

• React Native. @invertase/react-native-apple-authentication is the de facto standard. It fits most teams with React Native apps: it's actively maintained, supports Android through Apple's web-based flow, and documents integration with Firebase Auth. Expo projects can use expo-apple-authentication, Expo's own module, but it's iOS-only, so Android users need a separate web-based flow.

• Web. Apple's Sign in with Apple JS library handles browser-based sign-in. In Safari on Apple devices, users confirm with Face ID or Touch ID; in other browsers and on non-Apple devices, they enter their Apple Account credentials and confirm with two-factor authentication.

Whichever platform you're building for, verify the identity token server-side against Apple's public keys rather than trusting anything the client sends. And if your app supports account creation, it must also let users delete their account in the app; for Sign in with Apple users, that means revoking their tokens through Apple's REST API.

Apple also introduced two changes in 2026. Since January 1, 2026, developers based in South Korea must register a server-to-server notification endpoint when creating or updating a Services ID. And Apple announced in August 2026 that new private relay addresses will be issued on private.icloud.com instead of privaterelay.appleid.com, so any email validation or allowlist that hard-codes the old domain needs updating. Existing relay addresses keep working.

Configuring Sign in with Apple in Apple's Developer Console

Here’s a short list of things that need to exist in Apple’s Certificates, Identifiers & Profiles console before any platform code runs:

• An App ID with the capability enabled. Register your app's App ID, then explicitly enable the Sign in with Apple capability. It's an easy step to miss in apps that add the feature after launch.

• A Services ID. This is a separate identifier from your App ID, associated with your primary App ID, and it's what web and Android flows use as their client ID.

• Domain and Return URL registration. Once the Services ID exists, register your domains and add every Return URL your app will redirect to, exactly as written, including the scheme. Apple no longer asks you to upload a verification file, but a single typo in a Return URL is enough to break web sign-in.

• Registered email sources. If you plan to email users who chose private relay, register your outbound domains or addresses under Sign in with Apple for Email Communication.

• A private key, downloaded once. You can download the private key for Sign in with Apple only once, so store it immediately in a secrets manager. If you lose it, you'll have to create a new key and update every service that signs requests with it.

• Backend credentials assembled from the above. To exchange authorization codes or revoke tokens, your backend signs a client secret with that private key, using your Team ID, the Key ID, and your client ID (the bundle ID for native apps, the Services ID for web).

Get these in place before writing platform code, and you avoid configuration errors that otherwise surface later as hard-to-trace sign-in failures.

Strategic Takeaway: Treat the Sign in with Apple Requirement as Launch-Day Architecture

There are two versions of every Sign in with Apple integration: the one built in from day one, and the one bolted on the week after a rejection notice. The second one costs you at least one more trip through App Review. Details like one-time-only user data, private relay emails, token revocation, and platform-specific libraries are expensive to retrofit under deadline pressure.

The same goes for platform compliance requirements in general: treat them as architecture decisions made early. Pushed to a late-stage checklist, they show up as a blocked launch.

Building or updating an app that needs to meet Apple's login requirements? Talk to Monterail's mobile team about getting your authentication flow right the first time.