Play with your app's design.Right in the browser.
Drop your build, turn the knobs, export the code.
In your browser, or straight from your agent via MCP. Every colour, font, radius and spacing in its CSS becomes a knob, and the real app follows 1:1. Nothing is sent to a server and nothing is stored: close the tab and it is all undone. The code comes out as a patch, design tokens, or a DESIGN.md for your agent.
✓ Free · ✓ Open source (MIT) · ✓ Your files never leave your browser
Drop the built site: its dist/, build/ or out/ folder, a zip, or a public GitHub or GitLab repo. It renders 1:1 in the browser; nothing is sent to a server (files are read in the page and served to the frame by a service worker on this origin).
Knobs: brand and the colour families your CSS contains, background, fonts, text size, line height, letter spacing, weight, spacing, radius, border width, elevation, motion, gradient angle, hue, saturation, contrast, your dark mode. Export: CSS, JSON, a patch, your files patched, design tokens, Swift and Android constants. Free, MIT. Source · llms.txt · MCP server