BANGALORE, India — American technology companies desperately want to win over people like Rakesh Padachuri and his family.

Mr. Padachuri, who runs a construction business in this city, the center of India’s technology industry, uses his smartphone to reserve movie seats through BookMyShow and to order pizzas from Domino’s. His wife, Vasavi, orders clothes from Myntra and Amazon.com, and downloads videos and games from YouTube and the Google Play store to entertain their 4-year-old daughter. His sister-in-law, Sonika, enjoys posting selfies on Facebook and follows the YouTube musings of Lilly Singh, an Indo-Canadian comedian.

They all stay in touch via a group chat they have set up on WhatsApp, a free messaging service owned by Facebook. “There’s no need to call each other,” Mr. Padachuri said last month during an interview at his home, which is next to a Best Western hotel. There’s barely a need to leave the house — groceries, a birthday cake, even a hairdresser can be summoned via an app.

The Padachuri family’s love of technology helps explain why India and its 1.25 billion residents have become the hottest growth opportunity — the new China — for American Internet companies. Blocked from China itself or frustrated by the onerous demands of its government, companies like Facebook, Google and Twitter, as well as start-ups and investors, see India as the next best thing.