Hubble.md

Hubble.md is a free, open-source desktop notetaking app built by Ben Holmes (@bholmesdev) and licensed under the MIT License. It stores notes as Markdown and HTML files on disk, making it equally accessible to human writers and AI coding agents. The project is written in TypeScript, ships as an Electron desktop app, and currently supports macOS with Windows and Linux support described as forthcoming.

What It Is

Hubble.md is a local-first notetaking application that combines a familiar rich-text editing experience with full Markdown file compatibility. Unlike cloud-locked note apps, Hubble stores everything as plain .md or .html files in a folder on your machine, so any tool — including AI agents — can read and write notes directly. The editor supports / commands, Markdown shortcuts, and file frontmatter/properties, giving it a feel similar to Notion or Apple Notes while remaining grounded in open formats.

Agent-Ready Architecture

A core design goal of Hubble is to work seamlessly alongside AI coding agents. Because notes live as plain files on disk, you can point an agent at your notes folder and let it edit, create, or reorganize files. Hubble live-reloads as the agent makes changes, so the human and the agent effectively collaborate in real time on the same workspace. This positions Hubble as a notepad that bridges personal knowledge management and agentic workflows.

HTML Apps and Custom Views

Beyond standard Markdown notes, Hubble supports building and viewing HTML-based apps inside the same workspace. The README describes the "hubble-skills" plugin system that lets a coding agent generate custom views — turning a folder of notes into a table, a bookshelf, a map, or any other HTML interface. This extensibility layer is what distinguishes Hubble from a plain Markdown editor.

Repository Structure and Build Path

The project is organized as a pnpm monorepo with several packages:

• apps/desktop — the main Electron desktop app
• apps/web — the Astro-powered landing page
• apps/www — a React + Convex web app (marked as heavily work-in-progress)
• packages/editor — a framework-agnostic Markdown editor core built on Tiptap
• packages/sync — a filesystem sync engine (heavily work-in-progress)
• packages/cli — a hubble CLI for syncing a folder from the terminal

Building from source requires Node.js, pnpm, and on macOS, Xcode Command Line Tools. A production desktop bundle is generated under apps/desktop/release/.

Update: desktop-v0.1.12

The latest release is desktop-v0.1.12, published on June 23, 2026, reflecting active development. The repository was created in February 2026 and has seen consistent pushes through mid-2026. The web app and sync engine are explicitly marked as heavily work-in-progress, signaling that the desktop app is the stable surface while cloud sync and browser access are still being built out. Contributions are welcomed, and the project maintains a Code of Conduct and security policy.