Incremental software development is a process in which programmers add one program property at a time. During the process, programmers deal with large volume of knowledge, such as domain concepts and design decisions. This knowledge can be useful for software maintenance and debugging process. However, due to the fact that it is evolvable, it cannot be fully recovered from the final source code or documentation. Therefore, a tool is needed to document this knowledge during incremental software development.KRecorder is a prototype tool built on the Eclipse platform, and based on the cognitive activities recognized: absorption, reorganization, denial and expulsion. It allows users to record the domain concepts and design decisions on the fly while they are implementing an application. The ASTParser in the Eclipse is used to parse the source code and extract all necessary information. With KRecorder, the design and implementation process of an application can be well documented and displayed, and therefore, can be used during maintenance and debugging.