Ocean Brain

Self-hosted, open-source Notion alternative with bi-directional links and privacy-first design.

Own your notes. Connect your thoughts. No cloud required, no subscription needed.

Just like the vast ocean holds countless treasures, Ocean Brain lets your thoughts flow freely and securely on your own server.

Why Ocean Brain?

• Privacy-first: Your notes stay on your server. No third-party access, ever.
• Notion-like editor: Block-based editing powered by BlockNote
• Bi-directional links: Connect notes with [ and see backlinks instantly
• Zero subscription: Self-host once, use forever
• Quick setup: One npx or docker command, ready in 30 seconds

Try it now

Live Demo - See Ocean Brain in action

Quick Start

npx (Easiest)

npx ocean-brain

That's it! Open http://localhost:6683 and start writing.

Docker

docker run -d \
    -v ./assets:/assets \
    -v ./data:/data \
    -p 6683:6683 \
    baealex/ocean-brain

From Source

pnpm install
pnpm build
pnpm start

Features

Feature	Description
Block editor	Notion-like editing with / commands
Bi-directional links	Link notes with [ and track backlinks
Knowledge graph	Explore connections between notes visually
Tags	Organize with @ mentions
Search	Full-text search across all notes
Pin notes	Keep important notes at the top
Reminders	Set reminders with priorities
Calendar view	See your notes by date
MCP server	Integrate with AI tools like Claude Code

MCP Server (AI Integration)

Ocean Brain includes a built-in MCP (Model Context Protocol) server, allowing AI tools like Claude Code to search and read your notes.

Setup

Add to your Claude Code MCP config (.mcp.json):

{
  "mcpServers": {
    "ocean-brain": {
      "command": "npx",
      "args": ["-y", "ocean-brain", "mcp", "--server", "http://localhost:6683"]
    }
  }
}

Replace http://localhost:6683 with your Ocean Brain server address if running remotely.

Available Tools

Tool	Description
search_notes	Search notes by keyword
read_note	Read full content of a note by ID
list_tags	List all tags with note counts
list_recent_notes	List recently updated notes