A company could spend millions on a website and still not know how fast it loaded for real customers. Keynote Systems placed measurement computers across the internet and tested sites around the clock. Its public speed rankings of major sites made executives pay attention. When it filed to go public in the fall of 1999, slow pages were costing online businesses sales.

An Outside Referee

Keynote bet that web performance would need an outside referee. Most companies had no outside measure of their own site at all. Keynote measured download times and availability from many locations, the way a customer would see them, and sold the results as a subscription. Its public index of major sites' speed gave it visibility. It turned performance into a number executives could track, compare and improve.

Thoma Bravo Pays $20

Keynote priced at $14 a share in September 1999, under longtime chief executive Umang Gupta. It raised a large pile of cash during the boom and kept much of it through the downturn. It used some of that cash to buy related businesses, including mobile testing. In 2013 Thoma Bravo took Keynote private for $20 a share, about $395 million. Gupta retired as chief executive after the sale closed.

Cover: Woman at the Piano, Pierre-Auguste Renoir. Art Institute of Chicago, public domain. Chosen for a woman at the piano (the keynote, finding the right pitch).