New software applications allow homeowners to lock doors, adjust the thermostat, lower blinds and even power up the Jacuzzi on the deck using their mobile devices — from anywhere in the world.

“Manufacturers are catching on, and they can make apps for just about anything,” said Jonathan Stovall,of Bethesda Systems, a home automation company. “It’s all plug-and-play. A lot of products you can buy over the counter. They are really easy to use.”