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WebPerf Snippets

WebPerf Snippets is an MCP server that runs curated WebPerf Snippets headlessly via Playwright. Diagnose Core Web Vitals beyond what Lighthouse exposes and gate CI on real performance budgets. It has 1,454 GitHub stars, is released under the MIT license and runs locally with npx -y webperf-snippets.

github.com/nucliweb/webperf-snippets (opens in a new tab)

Data as of from the GitHub API and the official MCP registry; description from the project's repository. Report an error

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Install WebPerf Snippets

Generated from the server's MCP registry entry. Replace your-value with your own values.

Claude Desktop

claude_desktop_config.json
{
  "mcpServers": {
    "webperf-snippets": {
      "command": "npx",
      "args": [
        "-y",
        "webperf-snippets"
      ],
      "env": {
        "CRUX_API_KEY": "your-value"
      }
    }
  }
}

Settings > Developer > Edit Config. macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\. Restart Claude Desktop afterwards.

Claude Code

claude mcp add --env CRUX_API_KEY=your-value --transport stdio webperf-snippets -- npx -y webperf-snippets

Cursor

.cursor/mcp.json
{
  "mcpServers": {
    "webperf-snippets": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "webperf-snippets"
      ],
      "env": {
        "CRUX_API_KEY": "your-value"
      }
    }
  }
}

Project file; use ~/.cursor/mcp.json to enable it in every project.

VS Code

.vscode/mcp.json
{
  "inputs": [
    {
      "type": "promptString",
      "id": "crux_api_key",
      "description": "CRUX_API_KEY",
      "password": true
    }
  ],
  "servers": {
    "webperf-snippets": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "webperf-snippets"
      ],
      "env": {
        "CRUX_API_KEY": "${input:crux_api_key}"
      }
    }
  }
}

Config formats checked against the official docs on Oct 7, 2026: modelcontextprotocol.io (opens in a new tab), code.claude.com (opens in a new tab), cursor.com (opens in a new tab), code.visualstudio.com (opens in a new tab).

Environment variables

Variables the server reads at startup.

NameRequiredDescription
CRUX_API_KEYsecretNoChrome UX Report API key for the field data of get_crux; the other tools work without it

About WebPerf Snippets

Run curated WebPerf Snippets headlessly via Playwright. Diagnose Core Web Vitals beyond what Lighthouse exposes and gate CI on real performance budgets.

  • performance
  • performance-analysis
  • performance-metrics
  • snippets
  • webperf
  • webperformance
  • webvitals
  • agent-skills
  • ai-agents
  • chrome-devtools

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FAQ

WebPerf Snippets FAQ

Still curious? Email info@appsgit.com.

How do I install the WebPerf Snippets MCP server?

Add the command npx -y webperf-snippets to your MCP client: put it in claude_desktop_config.json for Claude Desktop, run claude mcp add for Claude Code, or add it to .cursor/mcp.json (Cursor) or .vscode/mcp.json (VS Code). The snippets on this page are ready to paste.

Is WebPerf Snippets free?

The server is open source under the MIT license, so running it is free. It needs credentials (CRUX_API_KEY) for the service it connects to, which may require a paid account.

Is WebPerf Snippets actively maintained?

The most recent commit was on Oct 26, 2026. The latest release is v2.1.0, published Oct 25, 2026. appsgit only lists MCP servers with a commit in the last six months.