Ookla is making the data available to help consumers, ISPs (Internet service providers) and regulators make more informed decisions, Apgar said. Previously, the company has provided raw data to researchers and companies through one-on-one arrangements. It also provides some data to ISPs, which can present Ookla's broadband-testing tools to their subscribers under their own brands.

Though the speeds may appear high for nationwide or citywide averages, Ookla says Speedtest detects more than just the bandwidth that a single PC browser can consume. It uses multiple threads of data to determine the full capacity of an Internet connection, which could be used by several devices around a home, Apgar said.

At least 90 percent of the results on which the index is based came from wired, residential broadband connections, which is the focus of the index, Apgar said. Ookla can detect a cellular session by the name of the ISP and manually filters out the results of tests that were probably conducted from a business, he said. Test results from Clearwire's WiMax wireless broadband service are included.

How much bandwidth consumers can actually get is a heated topic in the U.S., where various factions are debating how best to make more and better broadband available. The U.S. Federal Communications Commission has had a program to encourage consumers to measure and report their Internet connection speeds, using tools including Speedtest.

Free Press, an activist group on broadband issues, commended Ookla for making the data public but called it unscientific. Most importantly, Speedtest results come from users who know about the service and are interested enough in their broadband performance to test it, said S. Derek Turner, research director at Free Press.