Seeking to head off escalating scrutiny over Internet privacy, a group of online tracking rivals is building a service that lets consumers see what information those companies know about them.

The project is the first of its kind in the fast-growing business of tracking Internet users and selling personal details about their lives. Called the Open Data Partnership, it will allow consumers to edit the interests, demographics and other profile information collected about them. It also will allow people to choose to not be tracked at all.

When the service launches in January, users will be able to see information about them from eight data and tracking firms, including BlueKai Inc., Lotame Solutions Inc. and eXelate Inc.

Additional tracking firms are expected to join once the system is live, but more than a hundred tracking firms and big Internet companies including Google Inc. and Yahoo Inc. are not involved.

The companies involved represent some of the most aggressive trackers of Internet users, many of which have been profiled in The Wall Street Journal's "What They Know" series about online privacy. (See related article on page B2.)