Velloo

Decide the design with your agent.

Velloo is a free, open-source design canvas that sits beside your app. Your coding agent draws directions on it from your real components, you and your team react to the pixels, and the agent builds the one you choose.

Quickstart · Watch the film · Docs · Roadmap · Discussions

Quickstart

npm install -g velloo
cd your-app        # or an empty folder, to start something new
velloo init        # opens a setup page in your browser

The setup page reads your app (its components, theme and routes) and asks only what it can't tell. Then the canvas opens with your agent already at work in the Agent tab. In an existing app it starts with setup: it imports your theme and fonts, checks that your components render, and proposes a design language for you to review.

Then ask for what you came for:

Explore three different directions for the billing page, side by side on one board. Show me the canvas before you change any app code.

velloo run reopens the canvas later. init never changes your app's source.

• Which agents. The Agent tab runs Claude Code, Codex, or any installed agent that speaks the Agent Client Protocol (OpenCode, GitHub Copilot, Cursor, Gemini CLI and more), on your own login and subscription.

• Already working in a terminal? Tick your agent on the setup page or run velloo connect, then ask it to "Set Velloo up for this app" (/velloo:setup in Claude Code). A Claude Code or Codex session from your terminal can also continue in the Agent tab.

• Let the agent see its work. velloo browser install adds the optional headless browser it uses for screenshots.

• Other installs. pnpm add -g velloo, or the standalone installer in the quickstart guide.

Velloo is early and moving fast, so expect rough edges. velloo upgrade updates the tool and migrates your designs. Bug reports and design feedback are very welcome.

Related MCP server: Aceto

How it works

1. Explore. One prompt, several directions, drawn live on the canvas from your real components.

2. Refine. Pin comments and hand them to the agent, select something and ask for a change, or edit props and styles yourself.

3. Review (optional). Publish a board to a share link. Reviewers comment in their browser for free, and their notes come back to your canvas and your agent.

4. Ship. The agent writes the chosen design into your app, in its own framework, and compares the running app to the design.

Every screen follows your design language (colour, type, shape and written rules), which your agent proposes from your app and you approve on the canvas.

Each screen is saved as a readable component tree in a folder you own, so your agent edits exactly what you see. Concepts →

What you can do

Works with your stack

Agents outside the canvas connect over MCP: Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode, Windsurf and other MCP clients (connect an agent). Velloo runs on macOS, Linux and Windows.

Private by default

• Local and free. The canvas needs no account and sends no telemetry. Its only request of its own is an anonymous, at most daily check for a new release (VELLOO_DISABLE_UPDATE_CHECK=1 turns it off).

• Your agent, your login. The Agent tab starts your agent on your machine. Velloo holds no provider credentials, and the session never goes through Velloo Cloud.

• Cloud only when you ask. Velloo Cloud is opt-in (velloo login) and starts free: 3 live share links and 250 MB of storage, and reviewers never need a seat. velloo publish uploads what your machine rendered; the cloud never runs your app's code. Pricing →

Learn more

• Docs: guides, concepts and reference (CLI, MCP tools, themes).

• What's new in each release.

• Why I created Velloo, the thinking behind it.

• How Velloo is built: architecture, MCP surface, writing a framework adapter.

Contributing

Bug reports, adapters, docs and design feedback are all welcome. Start with CONTRIBUTING.md for setup and checks, and AGENTS.md for the package layout and architecture rules.

bun install
bun run --cwd packages/canvas build         # build the canvas
bun run velloo init /tmp/velloo-smoke
bun run velloo run /tmp/velloo-smoke        # canvas on :7300
bun run verify                              # typecheck, lint and tests

Planned work is on the roadmap. Small issues are labelled good first issue, larger ones ready to pick up help wanted.

Community and support

• Questions and ideas: Discussions

• Bugs and feature requests: open an issue

• Security issues: SECURITY.md. Please don't file a public issue.

• Ground rules: CODE_OF_CONDUCT.md

License

Velloo is open source under the Apache License 2.0.

The Velloo name and the interlinked-frames mark are trademarks and aren't covered by the code license: fork the code freely, but don't ship a derivative under the Velloo name or logo. See TRADEMARK.md.