mobile authentication Startups

Clef is a passwordless two-factor authentication service founded in 2013 by Brennan Byrne and two college friends. Starting with a friends-and-family round of $150-175K, the company grew to 124,000+ websites using their solution and raised $3.1M in funding by the time of this interview. Growth was driven primarily by word-of-mouth and community trust-building, accelerated by a New York Times feature that gave them credibility and sparked organic adoption.