Companies that develop software have a pressure from customers to deliver better solutions, and to deliver solutions faster and cheaper. Many researchers have worked with suggestions on how to improve the development process; software process improvement. As software development is a very knowledge intensive task, both researchers and industry have recently turned their attention to knowledge management as a means to improve software development. This often involves developing technical tools, which many companies have spent resources on. But the tools are often not used in practise by developers and managers in the companies, and it is often unknown if the tools improve how knowledge is managed. In order to build efficient knowledge management tools, we need a better understanding of how the tools that exist are applied and used in software development. We present and analyse eight case studies of knowledge management initiatives from the literature. We found evidence of improved software quality, reduced development costs and evidence of a better working environment for developers as a result of these initiatives. Further, we examine success criteria in knowledge management codification initiatives, based on Intranet tools in medium-sized software companies. In addition, we investigate how knowledge management tools are used for different purposes by different groups of users in two software consulting companies. They use tools both as support for personalization and codification strategies. The consulting companies are two medium-sized Norwegian companies with 40 and 150 employees, which work in development projects that lasts from a few weeks to several years.