Following are the tools we used during the writing of the book. This appendix is not meant to be an exhaustive view of the market or an analytical comparison of competitors . For example, we have low demands on development tools. Our work is not high-volume production but cautious experimentation. About 90 percent of the code was handwritten in very simple text editors (often web-based editors). The only tool that was truly indispensable (besides the Google search engine) was the Iris packet sniffer.