This paper presents Lancet, a multi-platform software visualization tool that enables the inspection of programs at the binary code level. Implemented on top of the linktime rewriting framework Diablo, Lancet provides several views on the interprocedural control flow graph of a program. These views can be used to navigate through the program, to edit the program in a efficient manner, and to interact with the existing whole-program analyses and optimizations that are implemented in Diablo or existing applications of Diablo. As such, Lancet is an ideal tool to examine compiler-generated code, to assist the development of new compiler optimizations, or to optimize assembly code manually. Categories and Subject Descriptors D.2.6 [Software Engineering]: Programming Environments— graphical environments; D.3.4 [Programming Languages]: Processors—optimization General Terms Design, Experimentation Keywords visualization, optimization, instrumentation, assembler, binary code