Software provider Inc. said on Tuesday that it has acquired start-up Kieden Corp., which helps customers track sales leads generated with online advertisements on Google Inc..

Financial terms of the deal were not released by Salesforce, which sells Web-based software that companies use to manage their sales and marketing efforts.

Kieden's software would help Salesforce's business customers analyze the effectiveness of advertising they place on Google, said Rebecca Wettemann, an analyst with Nucleus Research.

The software works by identifying which keywords attracted Web surfers to click on a particular Google advertisement, then request product information. It attaches that data to a file that Salesforce software uses to track leads throughout the entire sales cycle -- from initial interest to completed sale.

This is a big step toward making it clear how much of a return on investment there really is from Google advertising, Wettemann said.

The service, which will be marketed as Salesforce for Google AdWords, will cost $300 a month per customer and be offered as an optional add-on to the basic software package.

Salesforce, the No. 6 provider of customer relationship management software by revenue, is betting that the new offering will help distinguish its product offering from those of competitors including Oracle Corp. and SAP AG, its two largest rivals.

Kieden has just four employees, compared to about 1,600 for Salesforce. Both companies are based in San Francisco.

Salesforce last week reported better-than-expected fiscal second-quarter earnings and raised its full-year financial forecasts, prompting analysts to say that the company is succeeding in fending off challenges from bigger rivals in the fast-growing market for Web-based business software.

The company's shares have climbed 61 percent over the past year, while the Nasdaq Composite Index has traded flat over the same period.