Neil Mitchell shares with us his enthusiasm for building development tools. We hear the story of how he built Hoogle in order to learn Haskell, why he created the Shake build system and what he hopes to accomplish with it, and how he uses hlint in his own development work. We discuss Haskell IDEs (including his own minimal ghcid) and briefly touch on a variety of other development tools and libraries that aim to improve Haskell development. Neil also shares a trick he uses for hunting and fixing space leaks in programs and libraries.