Why this made the list
A lot of people who want a smart lock are stopped by the idea of ripping out a deadbolt they like, or losing the ability to hand a physical key to a dog walker. This one solves that by leaving the exterior hardware and keys completely alone, adding automation only on the inside.
What it actually does
The lock attaches over the existing thumb-turn on the inside of the door, so the outside keyhole and existing keys keep working exactly as before. Wi-Fi is built into this 4th generation model, unlike some earlier August locks that needed a separate plug-in bridge accessory for remote access and app control. It runs on two CR123 batteries rated for roughly three months per set, and connects to Apple HomeKit (Siri), Amazon Alexa, and Google Assistant.
Who this is actually for
Anyone who wants app control and auto-lock without touching the exterior of the front door, especially renters or people who like their existing deadbolt and don't want to explain a new one to a landlord. It's also a fit for anyone who wants to keep handing out a physical key to certain people while still getting remote access for themselves.
What to weigh before buying
- Roughly three months per battery set is on the shorter end for a smart lock, so budget for buying CR123 batteries regularly, they're less commonly stocked than AA or AAA.
- It's a retrofit onto your specific deadbolt and thumb-turn, worth confirming compatibility with your exact hardware before buying.
- The exterior keyhole still works, which is the point, but it also means this isn't a fully keyless lock the way a full deadbolt replacement is.
The verdict
A smart way to add keyless entry without changing how the door looks or giving up your existing keys. The tradeoff is more frequent battery swaps than some competitors, worth accepting for the retrofit convenience.