Justin Spahr-Summers


I’m a Cocoa and Cocoa Touch developer with a deep interest in open source and functional programming.

I’ve created or helped create several popular open source projects, including:

  • ReactiveCocoa, a framework for functional reactive programming in Cocoa
  • Carthage, a simple, decentralized dependency manager for Cocoa projects
  • Mantle, a model framework for Objective-C that greatly reduces boilerplate
  • libextobjc, a library to extend the Objective-C programming language

… as well as some niche projects, like:

I’ve given a few talks as well:

To see more of what I’ve done, check out my GitHub profile. I’ve also occasionally written answers on Quora and Stack Overflow.