# UISandbox

Launches your web project inside a browser tab to tweak styling controls directly. It passes the resulting visual tokens straight back to your coding agent.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 6
- Author: Ideelab
- License: MIT · policy=link-only · description only; the file stays with the author
- Source: https://github.com/Ideelab/uisandbox
- Updated: 2026-10-22
- HTML: https://affpapa.org/en/nevibecode/mcp/uisandbox

## What it does

The server connects your coding assistant to an in-browser styling environment. It loads a local web project, converting computed styles into interactive sliders for typography and spacing. The agent uses tools like `load`, `open`, `set`, and `screenshot` to control the view. It inspects real pages instead of static mockups.

All rendering stays inside the browser tab through a local service worker, so project code never reaches an external backend. The tool requires a compiled web build, rejecting native mobile applications or raw WordPress themes. When styling is finished, updated design values return to the workspace as design tokens or patch updates.

## Requirements
- Needs: Node.js (commands run via npx)
- Environment variables: `UISANDBOX_URL` — keys and tokens: ask the human for the values, never commit them or put them in shared files.

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add --env UISANDBOX_URL=<UISANDBOX_URL> --transport stdio uisandbox -- npx -y uisandbox-mcp
```
Replace <…> with your own values

### Codex

**Platform CLI**
```bash
codex mcp add uisandbox --env UISANDBOX_URL=<UISANDBOX_URL> -- npx -y uisandbox-mcp
```
Replace <…> with your own values

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "uisandbox": {
            "command": "npx",
            "args": [
                "-y",
                "uisandbox-mcp"
            ],
            "env": {
                "UISANDBOX_URL": "<UISANDBOX_URL>"
            }
        }
    }
}
```
Replace <…> with your own values

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "uisandbox": {
            "type": "stdio",
            "command": "npx",
            "args": [
                "-y",
                "uisandbox-mcp"
            ],
            "env": {
                "UISANDBOX_URL": "<UISANDBOX_URL>"
            }
        }
    }
}
```
Replace <…> with your own values

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add -e UISANDBOX_URL=<UISANDBOX_URL> uisandbox npx -y uisandbox-mcp
```
Replace <…> with your own values

## When to use it
- adjust typography and palettes directly in the browser
- fix generic AI styling patterns across web interfaces
- export tuned theme tokens back to the repository
- verify computed styles against original layouts with the verify tool

## Example prompts
- Open the current web application in UISandbox to adjust its theme.
- Start UISandbox and inspect computed style changes on the active view.
- Apply the exported design tokens from UISandbox to the codebase.

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