Five-year-old Optimizely, a website optimization platform, has raised another $58 million. The Series C round brings the San Francisco-based provider's total funding to $146 million.

Optimizely plans to use the cash to move deeper into personalization. “Personalization has become a dirty word in our industry because vendors have consistently over promised and under delivered,” CEO Dan Siroker noted.

Index Ventures led the round, with participation from Andreessen Horowitz, Bain Capital Ventures, Battery Ventures and Benchmark Capital. Optimizely’s platform provides integrated A/B testing and personalization technologies to help enterprises create web and mobile experiences.

All About Experience

Siroker, a former product manager at Google who led analytics for Barack Obama’s 2008 Presidential campaign, refers to Optimizely as an “experience optimization platform.”

With this latest investment, it will continue to advance the Optimizely Experience Optimization Platform, which includes its personalization and testing products. Optimizely will also expand the Optimizely Partner Ecosystem.

“When (CTO) Pete Koomen and I founded Optimizely five years ago,” Siroker blogged yesterday, “very few companies had even heard of A/B testing, and optimization software was about the last thing anyone considered putting in their technology stack.”

Optimizely also announced triple-digit revenue growth. Siroker claims the company has more than doubled revenue every year for the past five years.

Siroker claims Optimizely is the most widely used website optimization platform among the Alexa top 10,000 websites and is the No. 1 mobile app optimization platform for iOS. It's also grown adoption across verticals including retail, travel and media, he said.

Getting Personal

“One of the most important reasons we’ve raised this money is to further invest in personalization,” he said.

The company earlier this month released Optimizely Personalization, the latest addition to its Experience Optimization Platform.

Optimizely’s Jon Noronha, Senior Product Manager at Optimizely, blogged earlier this month that the personalization platform “will do for personalization what we did for A/B testing: unlock the potential of an emerging innovative practice and make it accessible to companies of all sizes.”

Siroker said it enables organizations to deliver a great digital experiences without the worry of underlying technology.

Optimizely in January released Stats Engine, which added to the company’s experience optimization platform by delivering test results that are "always valid" and "freed from the limitations of traditional statistical analysis," company officials told CMSWire then.

Forrester Research characterized the online testing space as a growing one in early 2013, and it recognized Optimizely as one of the leaders.