We describe two improvised performances in which a variety of source materials are algorithmically mashed up, using software code that is created on stage before a live audience. Each of us works with an original programming language that we designed and implemented ourselves, with significant influence from the live coding movement. Blackwell’s Palimpsest is an experimental art language, used only in research settings, while Aaron’s Sonic Pi is a free open-source product that has more than a million users worldwide. Working together to transform found and re-purposed material in ways that step outside traditional genres, this creative technical work raises profound questions about the nature of copyright and authorship in the digital era.