Sparkle (auto-update)

Sparkle is the de-facto standard auto-update framework for macOS apps that ship outside the Mac App Store. It checks a vendor-controlled appcast XML feed, downloads the signed update package, verifies an Ed25519 signature, and replaces the installed app on the next launch. It has been the standard since the mid-2000s and is currently on the 2.x line.

Mac Note Taker ships Sparkle 2.9.1, bound to a public Ed25519 key whose private counterpart is held by the publisher. Updates are delivered as signed and notarized DMGs from a Hetzner-hosted appcast. The framework is non-sandboxed, which simplifies the install step but requires careful re-signing of Sparkle's helper binaries during the build to satisfy hardened-runtime requirements.