pen.dev

Overview

pen.dev is a vector design tool that connects interface work with software development and AI agents. It is best suited to designers and developers who want to shape designs and move them toward code in one workflow. Its open format and broad agent connections stand out, but the free plan’s generation caps constrain regular, high-volume use.

Key features

Components, variables, themes, scripts and shaders support reusable, adaptable design work rather than one-off screens. Figma and HTML import, along with sketch and image input, give users several ways to start. Exports include PNG, JPEG, WEBP and PDF alongside HTML, CSS and Tailwind, so pen.dev can serve both visual exploration and code-oriented handoff.

The .pen format is open JSON with a fully open schema, a practical benefit for teams that want design files in an inspectable format. Users can work with an integrated agent or connect external agents through MCP. Documented integrations include Claude Code, Codex, Gemini CLI, Antigravity, OpenCode, Kiro and Claude Desktop; integrated provider options include OpenAI, Anthropic, Google Gemini, Cursor, GitHub Copilot, xAI, OpenRouter and other API-key providers. This range is useful for workflows already built around those tools, though the number of agents that can run concurrently depends on the plan.

A Chrome extension imports webpages, and IDE extensions are available for Cursor, VS Code, Antigravity and Windsurf. The CLI installs through npm and requires Node.js 22.19 or later, a meaningful setup requirement for developers using it. For text-based AI requests made with a user's own provider credentials, inputs and outputs go directly from the device to that provider rather than through High Agency servers. Pen.dev says account data, operational metadata, cloud files and shared content are encrypted in transit and at rest and protected by access controls. Requests to pen.dev-provided models and image or SVG services pass through High Agency servers in real time and are not stored, logged or cached there.

Pricing

The pricing page says plans are coming soon and pen.dev remains free until they launch. The current plan structure gives readers a useful sense of the trade-offs, but the paid tiers are not yet the active offer.

Free is the sensible way to evaluate the workflow, but five Agent days and 25 monthly image and SVG generations make it a limited choice for sustained production. Pro is aimed at an individual who needs unlimited Agent days and up to three simultaneous agents; its 350-generation cap remains relevant for image-heavy work. Ultra raises the monthly generation allowance to 750 and parallel capacity to six, making it the more suitable tier for intensive multi-agent workflows. Enterprise is for organizations seeking tailored usage and procurement support. No trial is offered.

Platforms

Pen.dev supports API, extension, Linux, macOS, web and Windows. The mix of web, desktop and development-environment access suits teams moving between design and implementation, while the CLI's Node.js requirement may add setup for some developers.

Who it's for

Choose pen.dev if your design work benefits from reusable vector components, code exports and the option to connect an existing AI agent through MCP. The open .pen schema and import/export range are especially relevant to developers and design teams that want editable files and a route from visual work to implementation. It is a weaker fit if you need generous image generation at no cost or expect several agents to run in parallel without moving beyond the free tier.

Pros and cons

Pros

• Open JSON format with a fully open schema keeps design data inspectable.
• Figma and HTML import, sketch and image input, and exports to common image, document and code formats support varied design-to-development workflows.
• MCP connections, multiple integrated provider options and IDE extensions give developers several ways to bring the tool into existing workflows.
• Own-provider text AI requests bypass High Agency servers, while account and cloud data receive encryption and access controls.

Cons

• The free tier allows only five Agent days and 25 image and SVG generations per month, limiting sustained use.
• Free users can run only one agent at a time; parallel workflows require a paid tier once plans launch.
• The CLI requires Node.js 22.19 or later.
• Image and SVG requests using pen.dev's own services pass through High Agency servers, unlike text-based requests made with a user's own provider credentials.

Alternatives

For a broader comparison of tools in this space, see AI UI Design Generators and AI Wireframe Generators.

• UXPin is worth considering if a 14-day trial and a post-trial free tier with two prototypes and 50 AI credits better match your evaluation needs.
• Paper offers a free plan with unlimited viewers and editors and 100 MCP tool calls per week, making it an option when those collaboration allowances matter more than pen.dev's open design format.
• Figma Make is an alternative for readers who want a starter allowance of 150 AI credits per day and 500 per month, or a Professional Full seat with 3,000 monthly credits for $16 a month billed monthly.
• Starry is free to download and use without a subscription; its AI chat requires your own provider API key.
• Coherent is a free, open-source option with unlimited projects, 40+ validators with auto-fix and support for bringing your own LLM key.
• Relume may suit a web-focused workflow: its free Site Builder plan allows one project and one page, with read-only sharing and Webflow and React components.
• Visily offers a free Starter tier with 300 AI credits per month and limited boards and elements, or a Pro plan at $14 a month with 3,000 credits.
• UX Pilot offers the first design free and may suit readers comparing design generation alternatives.

Verdict

Pen.dev is a strong fit for designers and developers who want an open vector design format, code exports and agent connections in one workflow. Its main reason to choose is that breadth; its main reason to look elsewhere is the free plan's tight monthly caps and single-agent limit. It is worth adopting for measured exploration now, with heavier use dependent on the paid tiers launching.