Stop guessing which one. Put them side by side.

The grid says what these tools are. This says what builders did about it — one decision per person, changeable whenever you change your mind.

# Tool comparison — Gemini Canvas vs Pencil (pen.dev) vs Superdesign

Source: Kbaise, a directory of tools that work with Lovable projects.
Pick one and tell me why before writing any integration code.

## Gemini Canvas (gemini-canvas)
- URL: https://gemini.google.com/
- Category: AI design builders
- Cost: free — Free · $7.99–$249.99/mo tiers
- What it is: A side panel where Gemini writes and iteratively edits an artifact with a live preview. For UI it defaults to a single HTML file with embedded CSS and vanilla JS; you can explicitly prompt for React instead. Copy from the Code tab is the only export mechanism.
- Why builders pick it: The cheapest way to test a UI idea before spending Lovable credits on it. No repo integration, no MCP, no awareness of your components — everything it writes is a self-contained island you reconcile by hand.
- Full dossier: /api/public/tools/gemini-canvas

## Pencil (pen.dev) (pencil)
- URL: https://www.pen.dev/
- Category: AI design builders
- Cost: free — Free during early access
- What it is: A Figma-like canvas inside Cursor/VS Code/Windsurf, storing designs as JSON .pen files inside your project folder so they are git-versioned next to the code. Runs as an MCP server, so the agent reads the canvas as structured design context rather than as an image. Two-way: you can import existing components back onto the canvas.
- Why builders pick it: Names your exact stack as a first-class target — React + Tailwind + shadcn/ui. Draw the article template, and the drawing becomes real components. Because the .pen file lives beside the code, the design and the build cannot silently drift.
- Trap: Requires a local checkout via Lovable's GitHub sync — cannot touch the browser editor. Domain is mid-rename (pencil.dev → pen.dev), early access, no published pricing commitment.
- Wiring: MCP server; assumes Claude Code as the agent
- Full dossier: /api/public/tools/pencil

## Superdesign (superdesign)
- URL: https://superdesign.dev/
- Category: AI design builders
- Cost: mixed — Free tier · $20/mo flat
- What it is: Turns prompts into UI on an infinite canvas and writes production React + Tailwind into your repo via your coding agent. Its differentiator: it reads your existing codebase and design system first, so output matches conventions instead of generating a parallel island.
- Why builders pick it: The one that addresses 'my site looks like generic AI output' at the source. Because it inspects your design system, it has a real shot at emitting proper shadcn primitives rather than raw divs. Installs as a portable skill across 70+ agents.
- Trap: Needs a local repo like Pencil. The original IDE extension is explicitly no longer maintained — development moved to the web app plus the skill. A 2026 review reports real instability (broken logins, canvas crashes).
- Wiring: npx skills add superdesigndev/superdesign-skill
- Full dossier: /api/public/tools/superdesign

## Quick read

- Free with no card: Gemini Canvas, Pencil (pen.dev).
- Editor's picks: Pencil (pen.dev), Superdesign.
- No logged gotchas: Gemini Canvas.

## Rules
1. Prefer the free tier when no budget was stated, and say what the ceiling is.
2. Read the full dossier before integrating.
3. Fetch /api/public/models before writing any AI model ID.

Agents can fetch the same thing: GET /api/public/compare?slugs=gemini-canvas,pencil,superdesign