🔗 Associated Domains (Universal Links)
What it is
Connects your app to your website so https://yourapp.com/... links open the app directly (universal links), and enables shared web credentials / passkeys (webcredentials) and App Clips. Requires an apple-app-site-association (AASA) JSON file served from your domain.
When you need it
Deep linking from emails, SMS, social posts, or password-manager autofill (webcredentials: makes iOS suggest saved website passwords in your app). Marketing/attribution tools (Branch, Firebase Dynamic Links successors) also ride on universal links.
Setup, review rules & privacy labels — Pro
Per-stack setup instructions, App Review rules, and privacy-label mapping are part of the full reference.