Otto Smart Door Lock
This smart lock is a great addition to your home. Otto is it the smallest smart lock of the ones you can find out there, "it makes it the only digital lock able to take the place of a deadbolt," 2.6" diameter. Very sleek design with the option of 3 different finishes: silver, gold, and black which together complement a wide range of door hardware.
Otto has no keyhole, instead relies on your phone. It can unlock the door with a tap on the screen if your phone is in range, or you can set up a guest access through the app. It also rotates like a combination lock, which allows you to punch in a PIN in case your phone dies.
In my opinion its design is very clean and modern, and very convenient if you have people or kids coming home when nobody is there to open. The only downside I found is that Otto is pricier than the other options, it has no camera, and although a red light will show its batteries eventually can run out.
You can find more information about it on the website https://meetotto.com