Justin Kan (born 1983) is an American Internet entrepreneur and investor.  He is the co-founder of live video platforms Justin.tv and Twitch.tv, as well as the mobile social video application Socialcam. He is a partner at venture capital firm Y Combinator. His attempt to broadcast his entire life at Justin.tv popularized the term " lifecasting ". Kan also started a Reddit-style electronic music discovery platform, The Drop.
He also contributes to the technology news site TechCrunch  and co-founded Kiko Software, the first ajax based online calendar, with Emmett Shear.  Kan graduated from Yale University in 2005 with degrees in physics and philosophy.
Kan's " lifecasting " lasted about eight months. The novelty of Kan's concept attracted media attention, and resulting interviews with him included one by Ann Curry on the Today Show . Viewers accompanied Kan as he walked the streets of San Francisco, sometimes involved in both pre-planned events (trapeze lesson, dance lesson) and also spontaneous situations (being invited into the local Scientology center by a sidewalk recruiter).
Afterward, the company decided to transition to providing a live video platform so anyone could publish a live video stream. Justin.tv, the platform, launched in 2007   and was one of the largest live video platforms in the world with more than 30 million unique users every month.
After Justin.tv launched in 2007, the site quickly began building subject-specific content categories like Social, Tech, Sports, Entertainment, News & Events, Gaming and others. Gaming, in particular, grew very fast and became the most popular content on the site. 
The company then decided to spin off the gaming content under a separate brand at a separate site. They named it TwitchTV, inspired by the term twitch gameplay. It launched officially in public beta on June 6, 2011.
Socialcam launched March 7, 2011, was bought by Autodesk July 17, 2012 for $60M and was ended by Autodesk October 28, 2015.    Socialcam was a mobile social video application for iPhone and Android. It allowed users to capture and share video online and on mobile, as well as via Facebook, Twitter, and other social networks.
The application at one point eclipsed 2 million downloads and continued to add features list, most notably with the addition of video filters. 
Justin Kan launched Exec (errand service) on February 29, 2012, a new service to allow anyone to outsource anything you want for $25/hour. Exec was co-founded with his brother Daniel Kan, former head of UserVoice business development, and Stanford graduate Amir Ghazvinian. 
Exec was purchased by Handybook, a company founded by Oisin Hanrahan, Umang Dua, Ignacio Leonhardt, and Weina Scott, in an all-stock transaction January 2014.
Kan was a member of the first batch of YC-funded startups in 2005 for Kiko Calendar, and was funded by YC again for Justin.tv and Exec. Kan became a partner at Y Combinator in March 2014, where he offered advice to the new startups in each batch. In March 2017, Kan left Y Combinator to start his own incubator, Zero-F.
The Drop is a Reddit-style electronic music discovery platform that launched early 2015. Users can post and up-vote community curated and sourced tracks. It was founded by college friends Ranidu Lankage and Justin Kan.