New York startups are proving that Silicon Valley isn't the only place where monstrous tech companies can be made.

In the past twelve months, three tech companies in the New York area have exited for more than $1 billion.

Connecticut-based Indeed, a job search site with a big Manhattan presence, was acquired by Japanese company Recruit Co. Ltd. for an estimated $1 billion. Travel search site Kayak went public then was acquired by Priceline for $1.8 billion.

Now Tumblr, a true New York City company, has been acquired by Yahoo for $1.1 billion in an all-cash deal. It's staying in New York post-acquisition, so the talent won't be departing for Silicon Valley.

Other recent, sizeable New York exits include Buddy Media, which was acquired by Salesforce for ~ $690 million and OMGPOP, which Zynga purchased for a ~ $200 million. 

The exits mean more capital to spawn companies and retain talent in New York. Tumblr was the result of an exit its founder, David Karp, was a part of in 2006. He was head of product for UrbanBaby when CNET acquired it and he used the capital to launch Davidville, a hub for his creative projects.

Tumblr won't be the last big exit New York sees either. Other valuable companies that are growing quickly include 3D printing company Makerbot and project funding site, Kickstarter.

- By Alyson Shontell