What Is HomeKit? The Protocol Under the Apple Home App
HomeKit is Apple's own accessory protocol, called HAP. Apple Home is the app you see; HomeKit is what the accessories speak underneath it. Since Matter arrived, an accessory in Apple Home may be talking HomeKit, Matter, or both, and the difference decides whether it needs a hub, whether it can be shared with Alexa or Google, and whether it can record to HomeKit Secure Video. Of the 27 accessories paired in this house, 10 are Matter and the other 17 are classic HomeKit.
Apple Home is the app. HomeKit is the thing underneath it that accessories speak. For years those were effectively the same decision, because if an accessory worked with the Home app it was running Apple’s protocol. Matter ended that, and a home set up today usually contains both.
HomeKit Is a Protocol, and Apple Home Is the Interface
HomeKit’s real name is the HomeKit Accessory Protocol, abbreviated HAP. It defines how an accessory describes itself, how it is paired, how it is encrypted, and how a command reaches it. When a lock reports that it is locked, or a plug accepts an instruction to switch off, HAP is the language carrying that.
The Home app is a client sitting on top. So are Siri and the Control Center tiles, and so is any third-party app that asks for access to your home. Change the app you use and the protocol underneath does not change.
This is why an accessory can vanish from the Home app while still being physically fine. What broke is the pairing or the network path, not the hardware.
HomeKit, Matter, and What Each One Handles
Matter is a competing application layer, built by an industry group rather than by Apple, and Apple supports it alongside HAP. Both do the same category of job: describe an accessory and carry commands to it.
The practical differences are narrow but they matter when buying:
- Sharing. A Matter accessory can be added to Apple Home and to Alexa or Google at the same time, because Matter defines how several controllers hold credentials for one device. A HAP-only accessory belongs to Apple Home alone.
- Setup codes. Matter pairs from an 11-digit code. HomeKit pairs from an 8-digit one.
- Apple-only features. Some things exist on Apple’s side of the line and nowhere else. HomeKit Secure Video is the significant one.
Neither is a network. Both run over Wi-Fi, Ethernet, or Thread, and which transport an accessory uses is a separate question from which protocol it speaks. HomeKit over Thread shipped years before Matter’s specification was public.
What the Hub Actually Does
A home hub is an Apple TV 4K or a HomePod that stays in the house and holds your home open when you are not there. Without one, HomeKit works while your phone is on the same Wi-Fi and stops working when you leave.
Four things need it:
- Remote access from outside the house.
- Automations that fire on a schedule or a sensor, with no phone present.
- Thread accessories, which reach your network through a border router built into the Apple TV or HomePod.
- HomeKit Secure Video, because the hub does the analysis of the footage.
Apple retired the original HomeKit architecture on February 10, 2026, and an iPad is no longer eligible as a hub. If your home ran on an iPad, that is the change that stranded it, and the migration path is a separate piece.
HomeKit Secure Video Is the Feature Without a Matter Equivalent
Cameras are where the HomeKit-versus-Matter question stops being academic. HomeKit Secure Video records encrypted clips to iCloud with no per-camera fee, and the analysis happens on your hub rather than on a manufacturer’s server. It runs on Apple’s protocol.
A camera that advertises only Matter will pair and stream, and it will have no route to HSV recording. Apple also caps HSV recording at 1080p, so a 2K or 4K sensor does not record at its full resolution through this path.
The Aqara G100 in this house is a worked example of how confusing the labelling gets. Its box carries badges for several ecosystems, but a scan of what it advertises on the network shows _hap._tcp only, HAP protocol 1.1, camera category. It is a HomeKit camera, and the other badges describe routes through Aqara’s own hub rather than direct support.
Reading the Box
Badges are marketing and they are printed for every ecosystem a manufacturer intends to reach, sometimes including ones that only work through the manufacturer’s bridge. Two checks are more reliable.
Look at the setup code. Eleven digits means Matter, eight means HomeKit. A box carrying both is telling you the accessory supports both.
Then look at what the accessory needs. If pairing requires the manufacturer’s own app and account before the device appears in Apple Home, it is bridged rather than native, whatever the badge claims.
Old HomeKit Accessories Keep Working
Two iDevices switches bought in 2017 still run here on firmware 1.9.11, from a company that was wound down after an acquisition, controlling lamps through the Home app every day. The protocol they speak has outlasted the company that shipped them.
That is the argument for caring which protocol an accessory uses. HAP accessories from a decade ago still pair, because Apple kept supporting them, and 17 of the 27 accessories in this house are still classic HomeKit rather than Matter. A device is not obsolete because a newer standard exists.
Common questions
Is HomeKit the same thing as the Apple Home app?
No. The Home app is the interface on your iPhone, iPad, Mac, and Apple TV. HomeKit is the protocol accessories use to talk to it, which Apple calls the HomeKit Accessory Protocol, or HAP. An accessory that supports Matter instead of HAP still appears in the same app.
Has Matter replaced HomeKit?
Not in the sense of switching anything off. Apple still supports HomeKit accessories, including ones sold years before Matter existed, and both kinds sit side by side in one home. What changed is that new accessories increasingly ship Matter, and some ship both.
Do I need an Apple TV or HomePod to use HomeKit?
For a single accessory controlled while you are at home on the same Wi-Fi, no. For remote access, automations that run when nobody is home, Thread accessories, and HomeKit Secure Video, yes. Since February 10, 2026, that hub must be an Apple TV 4K or a HomePod; an iPad no longer qualifies.
Can a Matter accessory use HomeKit Secure Video?
Camera recording through HomeKit Secure Video runs on Apple's own protocol, so a camera has to support HomeKit for it. A camera advertising only Matter will appear in the Home app but has no path to HSV recording.
How can I tell whether an accessory is HomeKit or Matter?
The box is unreliable, because badges are printed for several ecosystems at once. The dependable check is the setup code: a Matter accessory pairs from an 11-digit Matter code, usually with its own QR code, while a HomeKit accessory uses an 8-digit HomeKit code.
Runs the homekit.reviews test home, a real mixed Matter/Thread/HomeKit house. Everything reviewed here was set up, paired, and lived with. See how I test →