Sidera

Fast, visual notes on whiteboards — local, open and MCP-ready.

Sidera is a free, open-source, local-first app for fast, visual note-taking on whiteboards. Put text, tables, live charts, images and hand drawings on one infinite board — and take it to your iPad — instead of splitting the same idea across a dozen documents. Built MCP-first: every core action is an MCP tool, so Claude Desktop, Claude Code or any other MCP client can read and build your boards alongside you.

_{Everything above is one board: text, a table, eight charts, images, sketches and pen ink — built in Sidera.}

On your iPad, live

Press the iPad button on any board and it opens on your iPad — both ways, in real time, over your own Wi-Fi. A finger pans and zooms, Apple Pencil draws, everything else stays editable. End-to-end encrypted, no cloud, no App Store.

Charts that live on the board

Sixteen chart types — column, bar, line, area, combo, radar, pie, donut, waterfall, scatter, bubble, heatmap, sankey, timeline, 2×2 matrix and Venn — each backed by a small table you can edit in place, or linked to a table on the board so it redraws whenever the numbers change. Colour by value (everything below break-even in red), labelled markers, own axis ticks and titles, smooth or straight lines — and you can circle the bar that matters with the pen.

Features

• Whiteboards, first — an infinite canvas with text boxes (plain or framed, any size), tables, charts, images & PDFs, colored sections, labeled connectors, mindmaps, Mermaid diagrams and link previews. Rotate anything, undo/redo, ⌘F find, minimap and zoom.
• Live stock charts — drop a TradingView chart for any stock, index or crypto onto a board (overview or full candle chart): pick Stock chart… from the insert menu, paste a TradingView link, or ask Claude.
• Pen mode — sketch straight onto the board (P), with pen, highlighter, eraser, colours and widths. Ink is part of the board, not a layer on top.
• Sidera for iPad — the board live on your iPad as a home-screen web app; pair once with a QR code.
• Cards & backlinks — rich text (Tiptap) with / commands and @ mentions that create real backlinks; one card can live on any number of whiteboards.
• AI chat, bring your own key — an in-app Claude assistant (⌘J) that uses the exact same tools as the MCP server, so anything an external agent can do, it can do too. Optional native web search for Anthropic and OpenAI models.
• MCP server for every core action — 50+ tools over local HTTP or stdio: Claude can build whole boards — tables, linked charts, ink, flowcharts — and search and organize your cards, tags, kanban and tasks.
• Accounts & guest mode — local accounts with an optional password, or a temporary guest workspace that's wiped on sign-out. No cloud account, ever.
• Local-first — everything lives in ~/Library/Application Support/Sidera/ (SQLite + imported files); Markdown export/import any time.

Also included

A card library with tags, backlinks and SQLite FTS5 search (⌘K), tags-as-databases with kanban boards and lists, a split-screen PDF reader with highlights, and a Tasks area with list/board views, priority, assignee, due dates and an activity timeline.

More screenshots

Pen mode — draw right on the board	Home — boards first, with live previews
AI chat, same tools as MCP	Connect Claude in one command
Card library & ⌘K search	Tasks, across every card
PDF reader with highlights	Guided onboarding

_{All screenshots are generated from a scripted demo workspace (fictional companies) by node scripts/readme/shoot.mjs.}

Install

Download the latest DMG for your Mac (Apple Silicon arm64 or Intel x64) from Releases and drag Sidera into Applications. Sidera tells you when a new version is out (Settings → About; you can turn the check off).

Sidera is free and not yet notarized by Apple, so macOS blocks the first launch. Either open System Settings → Privacy & Security and click Open Anyway next to the Sidera message, or run once:

xattr -dr com.apple.quarantine /Applications/Sidera.app

You'll land on the sign-in screen — create a local account (password optional) or continue as a guest:

Connect to Claude (MCP)

While Sidera is running, it exposes a local MCP server with all of its tools (build boards with tables, charts and ink; search, create and organize cards, whiteboards, tags, kanban and tasks). Easiest way in: Settings → MCP & Claude → Connect everything, which wires up both Claude Desktop and Claude Code. Or from a terminal:

claude mcp add --scope user --transport http sidera http://127.0.0.1:3845/mcp

Headless (no UI) stdio mode is also available: Sidera --mcp-stdio. Your data never leaves the Mac — the server only binds to 127.0.0.1.

Sidera for iPad — the iPad button in a board's top-right corner (or ⇧⌘D) shows that board live on your iPad, both ways: edit text, cards, tables, shapes, add photos; a finger pans and zooms, Apple Pencil draws ink. Pair once with a QR code (Share → Add to Home Screen for the full-screen app); afterwards the iPad reconnects by itself whenever you share a board, and follows the board where you pressed the button last. Paired devices are listed (and revocable) in Settings → iPad.

How it works: the iPad app is a second build of the desktop renderer (vite.ipad.config.ts), served by the Mac on your private LAN address while an iPad is paired (it only sees a board while you share one). Every message is end-to-end encrypted (XChaCha20-Poly1305 under per-connection keys derived from a per-device key that was handed over once via the QR code fragment) with replay protection, and the Mac only answers a whitelist of calls scoped to the shared board (src/main/ipad/policy.ts). The protocol (src/shared/sync) is transport-agnostic: the LAN WebSocket can later be replaced by a cloud relay that only forwards ciphertext between device and Mac.

Build from source

npm install
npm run dev             # electron-vite dev, HMR renderer
npm test                # vitest, runs inside Electron's Node
npm run typecheck       # tsc for the node + web projects
npm run dist            # package a distributable app

Tech stack

Electron · electron-vite · React · TypeScript · Tailwind v4 · shadcn/ui · Redux Toolkit · Tiptap · SQLite (better-sqlite3 + Drizzle, FTS5) · React Flow · dnd-kit · cmdk · Motion · MCP SDK

Privacy

Sidera is local-first: your database and imported files live in ~/Library/Application Support/Sidera/. There is no Sidera server, no account in the cloud, no analytics and no telemetry. Accounts are local (scrypt-hashed passwords); guest workspaces are deleted on sign-out.

Sidera only goes online for things you trigger or can switch off:

• AI assistant — your messages go to the provider you picked (Anthropic, OpenAI, Gemini, Mistral, xAI, OpenRouter or your own endpoint), with your own API key. Keys are stored AES-encrypted in your data folder (readable only by your macOS user — no Keychain password prompts) or read from environment variables (see .env.example).
• Link previews & web clipper — fetch the page you add (private network addresses are blocked).
• Stock charts — load TradingView's embed widget for the symbol on the board.
• Update check — one request to the GitHub API per launch (Settings → About to turn it off).

The MCP server and the iPad sync only listen on your Mac (127.0.0.1) and your local network.

Contributing & security

Bug reports and pull requests are welcome — see CONTRIBUTING.md. Please report security issues privately as described in SECURITY.md.

License

MIT. Third-party licenses ship with the app (Settings → About → Open-source licenses).