SseStream is a tiny, zero‑dependency Node.js library that provides a writable stream for formatting and sending Server‑Sent Events (SSE) over HTTP. By creating an `SseStream` instance with the incoming request and piping it to the response, developers can easily push JSON‑compatible data, custom events, IDs, retry intervals or comments to browsers that support SSE. It’s aimed at backend developers building real‑time, push‑based APIs with Express, Fastify, or plain Node HTTP servers.