mod_swift is a technology demo which shows how to write native modules for the Apache Web Server in the Swift 3 programming language. The demo includes a C module to load Swift modules, a basic demo module, the ApacheExpress framework which provides an Express like API for mod_swift, a demo for ApacheExpress, a Todo MVC backend (w/ CalDAV support!), and a few supporting libraries (such as Freddy or Noze.io Mustache). This is a little different to something like mod_php which enables Apache to directly interpret PHP scripts. mod_php itself is C software and a single module. Since Swift compiles down to regular executable binaries, and because Swift has excellent C integration, you can write arbitrary modules with mod_swift which behave just like the regular C modules.