What is Hubble.md used for?

Hubble.md is a free desktop notepad for Markdown that feels like Notion or Apple Notes and is designed so AI agents can read, edit and build views on your notes. It is a good fit for collaborating with a coding agent on notes, turning a notes folder into a custom view and keeping notes in portable Markdown files.

Is Hubble.md open source?

Yes. Hubble.md is open source under the MIT licence. Its source code is on GitHub at bholmesdev/hubble.md and is written mainly in TypeScript.

Yes. Hubble.md is open source, so the software itself is free to use.

Can I self-host Hubble.md?

Yes. Hubble.md can be self-hosted on your own server or infrastructure; there is no official hosted version.

What is Hubble.md an alternative to?

Hubble.md is an open-source alternative to Notion, Bear, Ulysses and iA Writer. Other open-source alternatives to Bear include FSNotes, WitNote and Lumen.

Is Hubble.md actively maintained?

Yes. The most recent commit to Hubble.md was on 1 October 2026. The project has 1.5k stars on GitHub.

Hubble.md: open-source alternative to Notion, Bear, Ulysses

About Hubble.md

Hubble is a free, open-source note-taking app that stores notes as Markdown and HTML files in a folder you control. It aims to feel familiar to people used to Notion or Apple Notes, with slash commands, Markdown shortcuts and support for file properties and frontmatter, while keeping everything as plain files.

A key idea is working alongside AI agents. You can point a coding agent at your notes folder, and Hubble reloads live as the agent edits files. Beyond text, the app can display HTML-based apps, so with the right skills installed an agent can turn a folder of notes into a table, a bookshelf or a map, depending on what you ask for.

Hubble ships as a desktop app for macOS, Windows and Linux, with signed builds on macOS and unsigned builds elsewhere. It is written in TypeScript and licensed under MIT, and it can be compiled from source with Node.js and pnpm. It suits people who keep their notes in Markdown and want an editor that works smoothly with AI coding agents.

Key features

Markdown editing with slash commands
Frontmatter and file properties support
Live reload when agents edit files
HTML apps rendered from notes folders
Desktop apps for macOS, Windows, Linux
Notes stored as plain files

Good fit for

→Collaborating with a coding agent on notes
→Turning a notes folder into a custom view
→Keeping notes in portable Markdown files

Built with: TypeScript
Tags: note-taking; markdown; desktop-app; ai-agents; local-first; notepad; typescript; html-apps

Hubble.md: questions and answers

What is Hubble.md used for?: Hubble.md is a free desktop notepad for Markdown that feels like Notion or Apple Notes and is designed so AI agents can read, edit and build views on your notes. It is a good fit for collaborating with a coding agent on notes, turning a notes folder into a custom view and keeping notes in portable Markdown files.
Is Hubble.md open source?: Yes. Hubble.md is open source under the MIT licence. Its source code is on GitHub at bholmesdev/hubble.md and is written mainly in TypeScript.
Is Hubble.md free?: Yes. Hubble.md is open source, so the software itself is free to use.
Can I self-host Hubble.md?: Yes. Hubble.md can be self-hosted on your own server or infrastructure; there is no official hosted version.
What is Hubble.md an alternative to?: Hubble.md is an open-source alternative to Notion, Bear, Ulysses and iA Writer. Other open-source alternatives to Bear include FSNotes, WitNote and Lumen.
Is Hubble.md actively maintained?: Yes. The most recent commit to Hubble.md was on 1 October 2026. The project has 1.5k stars on GitHub.