Upgrade a standard deadbolt to a smart lock without changing the key. Only tool required is a screwdriver; very-not-handy grad student set up in < an hour. Good for rentals. Allows you to:

• Lock your door automatically each night
• Unlock your door with your phone
• Share lock privileges with anyone with the app
• Be notified when someone unlocks your door

Wirecutter's best budget smart lock/best smart lock for renters: https://www.nytimes.com/wirecutter/reviews/the-best-smart-lock/. Normally $130. Amazon link: https://www.amazon.com/dp/B085R7J5V4/?tag=thewire06-20&linkCode=xm2&ascsubtag=AwEAAAAAAAAAAkGg.

Used for two years, but still works well. Only selling because new dorm doesn't have a key. Requires wi-fi connection.