Kontagent is announcing today that its Facebook viral analytics tool is being used by companies with 50 million users on the social network. It also says it has raised $1.25 million in both institutional and angel funding.

The San Francisco-based company says it goes far beyond rivals such as Google Analytics to give Facebook developers a much more accurate picture of how their apps are doing. That’s critical because app makers like to tinker with their work to ensure they have the best chance to take off on Facebook, which has 400 million users.

Albert Lai, chief executive of the 10-employee firm, said in an interview that the company has worked for two years on its analytics platform. It released version 1.0 in December and is now broadly releasing version 1.5 to customers, which include a lot of big players in the social game market. The customers have 50 million monthly active users.

“In the past, these companies had to fly a plane with no dashboard,” Lai said.

Kontagent’s customers include PopCap Games, Real Networks, Gaia Online, TenCent, Paramount, PlayFirst, King.com, ThreeRings, Conduit Labs, MetaPlace and many other leading brands.

Kontagent was founded by Lai and Jeffery Tseng. It raised $250,000 from Facebook’s investment arm, the fbFund, last year. And it has raised $1 million in seed funding from angels including Jameson Hsu, co-founder of Mochi Media (acquired by Shanda Games); James Hong, co-founder of HotOrNot; Benjamin Sun, co-founder of CommunityConnect; Auren Hoffman, founder of RapLeaf; Greg Thomson, founder of TallTreeGames and creator of YoVille (acquired by Zynga); and Mike Sego, Chief Product Officer of Gaia and creator of (Fluff)Friends (acquired by SGN). These investors join existing seed investors Naval Ravikant from The Hit Forge and Extreme Venture Partners.

The company has a demo account set up to let visitors see what version 1.5 looks like. Lai gave me a demo of the tool and showed how quickly someone can get analytics information about their Facebook apps. The data goes beyond page views, time spent on site, and search-engine ranking. It shows how users are socially linked, the revenue from an app, the ability to test different scenarios (A/B testing), user demographics, the rates at which free users convert into paid users, traffic, retention, user location, engagement, insights, and benchmarks for rivals.

If companies wanted to get this data in the past, they pretty much had to create their own software to do it. Lai said most of the new customers have come aboard in the last 60 days. Over time, Lai said the company will launch analytics tools for other platforms, too. Here’s a slide deck that describes Kontagent’s analytics.