LAGUNA BEACH, Calif.—Facebook Inc. and its messaging app WhatsApp are the main drivers of booming Internet use in India, Vikas Jain, co-founder of Indian smartphone maker Micromax Informatics Ltd., said at the WSJDLive technology conference on Wednesday.

Unlike some rivals, Micromax isn't interested in making and promoting its own apps and Internet services on its phones and prefers to put the most-popular apps from other companies on the devices.

“We...