OpenZeppelin Nile is a deprecated CLI tool for developing and interacting with StarkNet projects written in Cairo. It includes essential components for compiling, testing, deploying smart contracts, and dApps, while offering a Runtime Environment (NRE) for scripting. Designed for extensibility, Nile supports customization through plugins. Despite its discontinuation, it provided a streamlined development experience with support for Python versions 3.9 to less than 3.10 and offered comprehensive documentation including quickstart guides, development tutorials, and plugin examples. For those seeking a maintained alternative, consider using Scarb.