In Brent Simmons' second blog post about shutting down Vesper, he mentions that Open Source is being considered:
> Some people have asked that we make it open source. The request is getting serious consideration, but I can’t make any promises.
> The code is all Objective-C. It’s an iOS 6 app with just enough changes to keep it working on iOS 7 and beyond. It knows nothing about size classes, presentation controllers, and so on. Doesn’t even use auto layout. It’s not an example of how you’d write an app these days.
> Some people have asked that we make it open source. The request is getting serious consideration, but I can’t make any promises.
> The code is all Objective-C. It’s an iOS 6 app with just enough changes to keep it working on iOS 7 and beyond. It knows nothing about size classes, presentation controllers, and so on. Doesn’t even use auto layout. It’s not an example of how you’d write an app these days.
http://inessential.com/2016/08/21/more_notes_on_vesper