App.net Founder and CEO Dalton Caldwell is not a fan of Facebook, which claims that his product is too similar to the social network’s app center. So after Caldwell wrote some not-so-kind words for Facebook Co-Founder and CEO Mark Zuckerberg, he broke away from the site and let the public decide if App.net — a paid social platform — is a worthwhile endeavor. Hoping to crowdsource fundraising efforts and raise $500,000 to get the company off the ground, Caldwell far surpassed that.

Our sister site, Inside Facebook, reports that thanks to generous donors, App.net had raised more than $700,000 as of Monday afternoon. Caldwell is hoping for App.net to be a legitimate alternative to sites such as Facebook and Twitter, which he feels have sold out to advertisers.

Caldwell described his vision for App.net a little deeper in his blog:

I believe so deeply in the importance of having a financially sustainable real-time feed application-programming interface and service that I am going to refocus App.net to become exactly that. I have the experience, vision, infrastructure, and team to do it. Additionally, we already have much of this built: a polished native iOS app, a robust technical infrastructure currently capable of handing ~200MM API calls per day with no code changes, and a developer-facing API provisioning, documentation, and analytics system. This isn’t vaporware.

To manifest this grand vision, we are officially launching a Kickstarter-esque campaign. We will only accept money for this financially sustainable, ad-free service if we hit what I believe is critical mass. I am defining minimum critical mass as $500,000, which is roughly equivalent to ~10,000 backers.

App.net has been building critical mass and will roll out soon. Caldwell addressed a critic of his product on his blog, writing what App.net will support.

Readers: If you’ve had the chance to check out App.net, what do you think?