Hubble.md

Hubble.md is an open-source notepad that stores everything as Markdown and HTML files. The core workflow is file-in, file-out: you create notes, tag them by topic, and the tool organizes them into a browsable structure. The interface shown on the project page groups notes by tag — travel, cooking, outdoors — and lets you navigate across them. Because the underlying format is plain Markdown, any process that can write a text file can add a note, which is the premise behind the ‘agent ready’ label.

The standout feature is the ‘Build any view’ capability. Rather than locking you into one list layout, Hubble.md lets you render custom HTML views over your note collection — a map view, a bookshelf, an index page. This is the differentiator from a standard Markdown editor: the data layer and the display layer are separated, so you can write a note in the same format whether you’re building a recipe index or a travel log, and then surface it differently depending on the context.

Hubble.md fits a narrow but real use case: a single user who wants local, self-hosted notes that an AI agent can write into as part of a larger workflow. It does not fit teams, it does not appear to offer search across large note collections, and there is no mobile app or sync layer described on the project page. The project is early-stage by any observable measure — 61 GitHub stars, a solo maintainer, no documented license on the validator pass. Teams that start here and grow past a few hundred notes will likely hit the ceiling of a flat file system before they hit any feature ceiling.