do-md/domd

DOMD is a Markdown editor that shows you formatted text as you type, rather than making you switch between a raw-text view and a preview. It is built around a custom rendering engine written from scratch, rather than reusing any of the popular existing rich-text editor frameworks like ProseMirror or Slate. The entire editing core weighs about 20 kilobytes compressed, which is very small for what it does. The editor is available in two forms: a web app you can open in a browser without installing anything, and a native macOS application. The Mac version is designed to feel as fast and minimal as a built-in system app. There is no project sidebar, no sync service, no account required. Files stay on your device. Large documents, up to a megabyte, open at roughly the same speed as small ones. One notable feature is a command-line tool called domd-cli that ships with the macOS build. It lets automated tools, scripts, or AI assistants send text directly into an open DOMD window. Tokens from a streaming AI response can be piped in and appear in the document in real time as formatted Markdown. The project's README includes a demo of this using an Alfred workflow that calls an AI API and streams the reply straight into the editor. The internals use a single, immutable data structure to represent the document state at all times. Typing, undo, redo, and AI-streamed content all go through the same mechanism, which keeps behavior predictable and makes only the changed parts of the document re-render. The licensing is split. The application code and helper libraries in the repository are MIT licensed, meaning you can read, change, and self-host them freely. The core rendering engine is distributed only as a compiled artifact under a noncommercial license, commercial use requires written permission from the authors.