Moshe Hogeg, CEO of Mobli and co-founder of Yo Twitter/@moshehogeg Simple notification app Yo has raised a $1.5 million seed round at a $5–10 million valuation, the company tells Business Insider.

The round, which closed last week, includes eight investors. The founders of China's Tencent led Yo's seed investment, putting in more than $250,000. Mashable founder Pete Cashmore, Betaworks, and notable angel investors also contributed to the round.

Yo is an app that lets users send push notifications to friends by pressing a friend's name. Users can't customize the push notifications; the only message they can send to friends is the word "Yo."

Since its launch in April, the Israel-founded startup has grown to more than 2 million downloads. Co-founder Moshe Hogeg says users are sending more than 2 million "Yos" per day. A new version of the app will be launched before the end of the month. Yo currently has three employees.

The Yo app. Business Insider

The app has been a punching bag for tech blogs and even comedian Stephen Colbert who stated, "When I first learned about an app that boils down all your communication into two letters, I expressed myself in one: ‘Y?’"

But Yo investor John Borthwick of Betaworks says he sees the app as a promising notification system that's paving the way for a new suite of apps.

"Over the past year we have seen a handful of apps that function exclusively in the notifications layer — i.e., the content lives in the the notification, the content is the notification," Borthwick wrote on Betaworks' blog. "We are fascinated by these uses of simple yes/no on/off communications tools...As the notification layer becomes the primary interface of alert-based information on your phone — as the OS’s allow navigation and controls in those alerts — there will emerge a new class of applications that mediate this layer for web sites, other apps and connected hardware."