Clarizen, a company offering online project management tools, has raised $12 million in Series E funding.

The round was led by Vintage Partners, with past backers Benchmark Capital, Carmel Ventures, DAG Ventures, and Opus Capital also investing. Clarizen has now been raised a total of $49 million, most recently announcing a $12 million round about a year ago.

The company says it continues to grow at a rapid clip, adding more than 100 new customers a month, with revenue up 300 percent year-over-year in 2011. Back in April, Clarizen launched an Android app (it already had one for iPhone) and a new product called Clarizen Anywhere, which allows users to manage their tasks through a browser plugin or as an add-on in Outlook.

Clarizen says it doesn’t plan to raise any more venture money, though that could change depending on its growth needs.