HomeKit has seen a slow-but-steady increase in the number of supported accessories since its introduction in 2014. Initially, lights, outlets, and thermostats were the most common. Today locks, fans, garage doors, and cameras are also starting to emerge on the market from reputable manufacturers, along with a slew of sensors.
Accessory manufacturers are required to go through Apple’s certification process in order to ship commercial products bearing the “Works with Apple HomeKit” badge. In a surprising move this summer, Apple made the HomeKit Accessory Protocol (HAP) specification available for hobbyists and makers at WWDC. 
A few years ago, I stumbled on the homebridge project, an open source implementation of HAP. This project makes it possible to integrate unsupported devices into HomeKit. The HAP implementation homebridge provides was previously reverse-engineered, which made me hesitant to go too far with the project. However, with Apple’s release of the HAP spec for hobbyists, I’ve gone all-in with homebridge for my unsupported devices. We have a non-trivial number of Z-Wave devices in HomeKit by way of Wink and homebridge, and it has worked incredibly well.
I have a few homebridge-related posts queued up for the next few days where I’ll share some details about setting up our old IP cameras, as well as building a homebridge plugin for an old outlet controller.