Sparkle is an open-source software update framework for macOS applications, developed on GitHub by the Sparkle Project with dozens of contributors. A framework, in macOS terms, is a packaged library that is embedded in an app bundle. Sparkle makes an app update itself, with no work required from the user.
The developer adds the framework to the Xcode project, for example through Swift Package Manager, and sets a SUFeedURL key in the app's Info.plist. That key points to an appcast: an RSS feed, uploaded by the developer to a web server, that lists the versions and their download archives. The included generate_appcast tool builds this feed from a folder of releases and also creates delta updates, small files with only the changes between two versions. Each update is checked with Sparkle's EdDSA signatures and Apple code signing before installation. The app's own name and icons appear in the update window, sandboxed apps are supported, and users can let updates download and install silently in the background. Sparkle supports macOS 12 and later.
Sparkle is free under the MIT license.