Use CAD Compare from AI assistants (MCP)

CAD Compare comes as a small MCP server (Model Context Protocol) that runs on your computer. Your AI assistant calls it to compare CAD files on your disk and gets structured results back. The files are read locally and never uploaded: neither to us nor to the AI provider; the assistant only sees the comparison result.

The MCP server will be available for download shortly. This page describes how it will work.

What your assistant can do

Tool		What it does
`compare`	Free	Compare two parts: identical, moved, or different, with the maximum deviation and mirrored-part detection. With Pro also the list of changed features (“through hole Ø6 → Ø6.5”).
`fingerprint`	Free	A shape fingerprint of a part that does not depend on its position, to recognise renamed copies.
`describe`	Free	Version, capabilities and licence status.
`compare_assembly`	Pro	Compare two assemblies: parts added, removed, renamed or replaced, quantities, moves, structure, and what changed in modified parts.
`find_duplicates`	Pro	Find files in a folder that are the same part (also when only moved), and mirrored left/right parts.
`render_diff`	Pro	A PNG picture of the differences (overview and close-up), so that assistants that can see images look at what changed.
`export_report`	Pro	Write a comparison report (HTML, printable as PDF) next to the files.

Set it up

Claude Desktop: download the bundle and double-click it. Claude asks for your licence key (optional; without it you get the free tools).

Other MCP clients (Cursor, Windsurf, VS Code, ChatGPT desktop and others) start it with npx; you need Node.js 20 or newer. Add this to the client's MCP settings:

{
  "mcpServers": {
    "cad-compare": {
      "command": "npx",
      "args": [
        "-y",
        "cad-compare-mcp"
      ],
      "env": {
        "CAD_COMPARE_LICENSE": "ccp_…"
      }
    }
  }
}

Claude Code:

claude mcp add cad-compare -e CAD_COMPARE_LICENSE=ccp_… -- npx -y cad-compare-mcp

Pro licence key

Sign in on your account page, create a key for each computer, and put it into CAD_COMPARE_LICENSE. The server checks it once and then works offline for up to 7 days. Keys can be revoked on the account page at any time.

Things to ask

Compare bracket_v1.step and bracket_v2.step and tell me what changed.
Are these two STEP files the same part, just moved?
Which files in ~/projects/frame are duplicates of each other?
Compare the assemblies gearbox_A.step and gearbox_B.step and list the changes for the change note.
Make a report of the changes between plate_rev3.step and plate_rev4.step.

Privacy

The comparison runs entirely on your computer. Only the licence check talks to our server: it sends the licence key and the plug-in version; no files, file names or results.