A developer released KillSwitch, an esoteric programming language explicitly designed to be difficult for large language models and coding agents to parse or generate. The project ships with an interpreter, a specification, examples, and benchmarks, and its site displays a "Sorry, only humans allowed" message; the benchmarks page states "Claude Opus 5 leads.
KillSwitch An esoteric programming language built to break LLMs and coding agents. promo.ks Run Sorry, only humans allowed Stack stdout Source code Explore KillSwitch Interpreter, specification, and examples Benchmarks View the benchmarks Claude Opus 5 leads
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