Pebble Smartwatch.

Pebble, the smartwatch maker that two years ago launched its business with a crowdfunding campaign on Kickstarter, is making all kinds of waves in the world of connected devices, where brands such as Apple, Google, Samsung and Amazon.com dominate.

George Zachary, a partner at Charles River Ventures and the first institutional investor in Pebble, said Wednesday that the company's revenue hit $43 million last year and will double in 2014. Speaking on stage at the Silicon Valley Open Doors Conference he called Pebble the fastest-growing start-up he's ever backed, a group that includes Twitter and Yammer, which Microsoft bought in 2012 for $1.2 billion. Zachary also sits on Pebble's board.