Leeo's Smart Alert Nightlight can turn your existing smoke detector into a smart one giving it similar functionality to the Nest Protect. Once plugged into an outlet, Leeo listens to the sound that your smoke detector makes and can send an alert to your phone if your smoke alarm goes off. In addition to alerting you that your home may be on fire, Leeo can also monitor temperature and humidity as well as serve as a nightlight with adjustable brightness.
Leeo can also dial for help or notify trusted friends or family members if an alarm goes off.
Leeo sells for $99, which is the same price as Nest Protect. While neither are exactly cheap, you may get more out of Nest with the new gesture-controlled UI.