Mozilla is offering an experimental add-on to its Firefox browser, which illustrates browser tracking graphically as the user moves between sites.
Collusion is part of Mozilla's work with the Ford Foundation to educate people about the privacy aspects of cookies and browser tracking. It builds a spider-style diagram of tracking as the user moves between sites.
A demo of the software shows how users are tracked between two sites that share an advertiser.
The add-on will enable people to see who is tracking them and to turn tracking off selectively, says Mozilla.
In time, the company intends to launch a full version of Collusion and use the information it yields to build a global database of anonymous tracking information "and make it available to help researchers, journalists and others analyse and explain how data is tracked on the web", the company said in a statement.
Last month, the US government announced it will introduce a Bill of Privacy Rights, which includes backing for a do not track (DNT) feature in all browsers.
The announcement comes amid a groundswell of privacy agitation from government and privacy lobbying groups on both sides of the Atlantic.
Google agreed to include DNT in its Chrome browser, in the wake of the announcement from the White House. Firefox has included DNT since February 2011.