What is an Apple Developer ID?
A Developer ID is a certificate from Apple that a developer uses to sign a Mac app that is distributed outside the Mac App Store. Apple names two kinds: Developer ID Application for apps, and Developer ID Installer for installer packages.
What it proves
The signature tells macOS who made the app and that it has not been altered since signing. Apple says that signing with a Developer ID, together with a notarization ticket, lets Gatekeeper verify that the software is not known malware and has not been tampered with.
What it does not prove
A signature says who signed it, not that the app is good. It does not say what the app does with your data. For that you need the developer’s privacy statement and, if you want, a network monitor.
Why it matters
Without a Developer ID, an app can only be signed ad hoc, and macOS cannot tie it to a developer. NotchStar 1.0.0 to 1.0.2 were signed ad hoc. Since version 1.0.3, on 9 October 2026, downloads are signed with a Developer ID.
Related
Check the signature yourself with codesign -dv --verbose=2 /Applications/NotchStar.app, or read is NotchStar safe. Developers should also read about the hardened runtime.