Seattle enterprise software vendor Apptio raised a whopping $16.5 million in a third round of funding that positions the company to pursue a public offering next.

Apptio will use the funding to push into new markets and generally grow its business. It plans to add 30 employees by the end of the year, after hiring 30 since January. It currently has 85 employees.

The series C round brings Apptio's funding to $37.5 million. The round was led by Shasta Ventures, with participation from current Apptio investors, including Andreesen Horowitz, Greylock Partners and Madrona Venture Group.

Apptio makes tools that enterprise technology managers use to monitor, analyze and report on their operations and spending.

In its funding announcement, Apptio said it has seen a 300 percent increase in bookings year-over-year, doubling the number of Fortune 1000 companies using its products. Customers include Alaska Airlines, Blue Cross Blue Shield, BNP Paribas, Cisco, Expedia, Hallmark, Starbucks and JPMorgan Chase.

"We are operating with a very strong cash position, but still received high interest from outside investors which ultimately influenced the timing of this financing round," Sunny Gupta, co-founder, president and chief executive, said in the release.

A spokeswoman said the company has no specific plans for an IPO at this time, but provided the following statement:

We do not anticipate taking another round of funding. We are managing the company in a way that builds shareholder value. Given our belief in the market opportunity and the capital we have to fund our growth, we believe we have a good shot at a very successful IPO.

Apptio could also become a target for acquisition by one of the major enterprise software companies building up their portfolios. Gupta sold his previous startup, iConclude, in 2007 for $60 million.