end-of-stream is a Node.js module that calls a callback when a readable, writable, or duplex stream has completed or failed. It supports legacy streams, streams2, and stream3, and provides options to customize the behavior, such as ignoring errors or focusing on either the readable or writable side of a duplex stream. This module is ideal for developers working with Node.js streams who need to handle stream completion or failure events in a concise and reliable manner.