Tack

A real-time collaborative whiteboard. Open a board, share the link, and everyone on it draws and edits together, with live cursors. It's built around a plugin interface for custom shapes and tools, and it has no paid dependencies: the only costs are a server and a Postgres database.

• tack-web/: the Next.js app. A Konva canvas on a Yjs document, plus the landing page, accounts and the admin interface.
• tack/: the Rust server (axum + yrs). One actor per open board relays edits and presence, enforces roles and limits, and saves to Postgres.

Browser (Next.js + Konva + Yjs) ──WebSocket /ws/boards/:id──▶ tack :8080 ──▶ Postgres
                                ──REST /api────────────────▶

HANDOFF.md has the design, the decisions behind it and what's left to do.

What it does

• Shapes, lines and arrows that stay attached, freehand, text with markdown, sticky notes, images, frames, database tables and architecture component cards
• Diagrams from code: DBML, and Mermaid flowcharts, ER, class, sequence and state diagrams; PlantUML sequence, class, state, activity and entity diagrams
• Groups, align, auto-arrange, snapping, templates, undo/redo, export as PNG, SVG or PDF
• Share links with edit and view roles; optional accounts with two-factor sign-in
• An admin interface: live rooms, users, boards, audit logs, settings and system health

Running it locally

You need Rust (stable), Node.js 20+, pnpm and Docker.

# Postgres, on localhost:5434
cd tack && docker compose up -d postgres

# The server, on :8080. Migrations run at startup.
cargo run

# The web app, on :3000
cd ../tack-web
cp .env.example .env.local
pnpm install
pnpm dev

Open http://localhost:3000 and start a board.

Configuration

The server reads these from the environment, or from a .env file in the repo root:

Variable	Default
DATABASE_URL	postgres://tack:tack@localhost:5434/tack
TACK_ADDR	0.0.0.0:8080
TACK_ALLOWED_ORIGINS	http://localhost:3000,http://localhost:3001	Default for the admin setting; origins allowed to open a WebSocket or call the API
TACK_APP_URL	http://localhost:3001	Base URL of the web app, for links in emails
TACK_MAX_BOARD_BYTES	20 MB	Default for the admin setting
TACK_ADMIN_EMAIL, TACK_ADMIN_PASSWORD		Creates the first superadmin at startup if there's none
TACK_SMTP_URL		e.g. smtps://user:pass@smtp.example.com. Without it, emails go to the log
TACK_MAIL_FROM	Tack <tack@localhost>	Sender of every email
TACK_TRUST_PROXY	off	Read client IPs from X-Forwarded-For; only behind a proxy that sets it
TACK_STORAGE_QUOTA_BYTES		Storage budget shown on the admin health page

The web app needs NEXT_PUBLIC_TACK_WS_URL and NEXT_PUBLIC_TACK_API_URL (see tack-web/.env.example).

Tests

cd tack && cargo test         # uses the dev Postgres when it's up, skips those tests otherwise
cd tack-web && pnpm test      # Vitest
cd tack-web && pnpm typecheck && pnpm lint

Smoke checks against a running server: pnpm smoke:sync, smoke:solo, smoke:full, smoke:presence and smoke:ping (set TACK_WS_URL / TACK_API_URL for another port).