Sparkle is open source software available under the permissive MIT license, and is developed on GitHub by the Sparkle Project with the help of dozens of valued contributors.
Sparkle is kept up to date with the latest Apple technologies: it uses ARC and Auto Layout and supports OS X versions 10.7 through 10.11 and Xcode 5.0 through 7.0.
Supports traditional Sparkle DSA signatures as well as Apple Code Signing, for ultra-secure updates. Sparkle also supports authentication for installing in secure locations. Support for sandboxing is currently under development.
Requires no code in your app, but also provides deep delegate support for maximum customization. Developers can make Sparkle work exactly as they need, and users can make Sparkle work as they prefer.
Your own branding, icons and app name are used - there's no mention of Sparkle. Works with any Mac app, whether it uses Cocoa, Qt, Xamarin, or otherwise.
True self-updating - no work required from the user. Users can also choose to automatically download and install all updates silently in the background.
With Sparkle, you're in good company. Here are just a few of the thousands of apps which use Sparkle: