MCP servers you can
try before you buy

Open your client's config file

Claude Desktop (macOS): ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json

Cursor: ~/.cursor/mcp.json (global), or .cursor/mcp.json inside a single project.

Windsurf: ~/.codeium/windsurf/mcp_config.json

Claude Code has no config file to edit — it uses a CLI command instead (step 3).

Paste the entry

Claude Desktop, Cursor and Windsurf all accept the same object under mcpServers. Swap the package name for the server you want:

{
  "mcpServers": {
    "security-scanner": {
      "command": "npx",
      "args": ["-y", "mcp-server-security-scanner"]
    }
  }
}

npm packages (swap into args): ai-cost-analyzer, mcp-server-security-scanner, data-aggregator-mcp, market-data-analyzer, seo-audit-tool, mcp-schema-designer, social-media-analytics, resume-optimizer, legal-doc-analyzer, mcp-api-doc-generator

Using Claude Code? One command, no file

Claude Code registers the server from a terminal instead of a config file:

claude mcp add --transport stdio <name> -- npx -y <package>

Run claude mcp list to see whether it connected. Add a key later with --env LICENSE_KEY=your-key placed before --transport.

Restart the client, then confirm it loaded

Claude Desktop: quit and reopen, then look for the server in the tools menu. Cursor: Settings → MCP lists its tools. Windsurf: reload Cascade's MCP panel. Claude Code: claude mcp list shows ✔ Connected.

Running npx -y <package> directly in a terminal looks frozen — that is correct. It is a stdio server waiting silently for an MCP client on stdin; it never prints a prompt or returns. Press Ctrl+C to exit, and let your client launch it for you.

Add your license key when you buy

Your key is shown on screen on the success page once Stripe reports the payment as paid — that page is the authoritative copy, so copy it there. Add it as an env variable in the same entry:

{
  "mcpServers": {
    "security-scanner": {
      "command": "npx",
      "args": ["-y", "mcp-server-security-scanner"],
      "env": {
        "LICENSE_KEY": "paste-your-key-here"
      }
    }
  }
}

Keys verify offline against a public key compiled into the package — no account, no phone-home. Lost your key? Recover it here.