Nash (formerly known as Once Upon) is an open-source middleware platform that enables AI models to interact with virtually any API, application, or file system by generating Python code and shell commands dynamically. Designed to function as a machine control plane (MCP), it allows language models to read from and write to tools such as Notion, Linear, CSV files, Spotify, and even blockchains, using a single local installation. Nash supports custom API keys and reusable tasks, making it adaptable for a wide range of automation and integration workflows powered by LLMs.