GroupDocs.Watermark MCP Server

MCP server that exposes GroupDocs.Watermark as AI-callable tools for Claude, Cursor, GitHub Copilot, and other MCP agents.

Installation

One-click installs pre-fill every supported setting: edit the placeholder documents folder after install (output defaults to the same folder); an empty GROUPDOCS_LICENSE_PATH runs in evaluation mode - point it at your license to lift limits.

More clients - ready-made configs for Claude Code, Codex CLI, Visual Studio 2022, Cursor, Windsurf, Cline, and JetBrains Rider live in install/generated/.

Requires .NET 10 SDK.

Run directly with dnx (recommended — no install step):

dnx GroupDocs.Watermark.Mcp --yes

Pulls the latest stable release on every invocation. To pin to a specific version (recommended for shared configs and CI), append @<version>:

dnx GroupDocs.Watermark.Mcp@26.9.0 --yes

Or install as a global dotnet tool:

dotnet tool install -g GroupDocs.Watermark.Mcp
groupdocs-watermark-mcp

Or run via Docker:

docker run --rm -i \
  -v $(pwd)/documents:/data \
  ghcr.io/groupdocs-watermark/watermark-net-mcp:latest

Native prerequisites

The underlying GroupDocs engine uses System.Drawing (GDI+) for some operations. When you run the server natively (via dnx or the global dotnet tool) on Linux or macOS, install the native libgdiplus library first:

Skipping this on Linux/macOS surfaces as DllNotFoundException: libgdiplus in the tool response. The simplest zero-setup option on Linux/macOS is the Docker image.

Available MCP Tools

All tools support PDF, DOCX, XLSX, PPTX, PNG, JPG, VSDX, and 50+ more document and image formats.

Example prompts for AI agents

Copy any of these into Claude Desktop, Cursor, or GitHub Copilot Chat after the server is connected. The AI agent will pick the right tool and arguments automatically — file names are resolved against GROUPDOCS_MCP_STORAGE_PATH.

1. Add a DRAFT text watermark: "Add a watermark with the text 'DRAFT' to report.pdf."
2. Stamp a logo image: "Use company-logo.png as an image watermark on every page of contract.docx, opacity 30%."
3. Inspect existing watermarks: "What watermarks does invoice.pdf contain?"
4. Strip old watermarks: "Remove all watermarks from final-draft.docx so I can ship it."
5. Inspect document structure: "How many pages does presentation.pptx have, and what are their dimensions?"

Licensing

The MCP server itself is MIT; the underlying GroupDocs.Watermark engine requires a license for production use. Without one the server runs in evaluation mode:

• The engine adds an extra evaluation watermark to processed output.
• A single server process can load at most 10 documents; further calls fail until the server restarts.

There are two ways to license the server.

License file — point GROUPDOCS_LICENSE_PATH at your GroupDocs.Total.lic. Works offline.

Metered (pay-per-use) — set both GROUPDOCS_METERED_PUBLIC_KEY and GROUPDOCS_METERED_PRIVATE_KEY. You are billed for what you actually process, which suits AI agents well because their usage is bursty and hard to predict up front. If both a metered key pair and a license file are configured, metered wins and the file is ignored.

Metered mode needs outbound connectivity. Usage is reported to GroupDocs servers, so air-gapped or firewalled deployments must allow that egress — or use a license file instead.

Call the get_license_status tool at any time to see which mode is active, and — under metered — the consumed quantity and remaining credit.

Keeping the private key out of your config

The metered private key is a secret. MCP client configs are plain files on disk, and a project-scoped .mcp.json is committed by convention, so prefer, in order:

1. Set the variables in your OS environment and leave them out of the config entirely. An stdio MCP server inherits its client's environment, so this works in every client. On macOS note that an app launched from Finder does not inherit shell exports — use launchctl setenv, or launch the client from a terminal.
2. Reference them indirectly if your client supports it (Claude Code expands ${VAR}; VS Code uses ${env:VAR} and ${input:...}).
3. A literal value in a user-scoped config (for example ~/.claude.json) is acceptable for a single developer.
4. Never commit a literal key in a project-scoped .mcp.json.

For Docker, forward the values without writing them into any file:

docker run --rm -i \
  -e GROUPDOCS_METERED_PUBLIC_KEY -e GROUPDOCS_METERED_PRIVATE_KEY \
  -v /path/to/documents:/data \
  ghcr.io/groupdocs-watermark/watermark-net-mcp:latest

To lift the limits with a license file:

• Get a free 30-day temporary license
• Purchase a license | Product page

Configuration

Usage with Claude Desktop

{
  "mcpServers": {
    "groupdocs-watermark": {
      "type": "stdio",
      "command": "dnx",
      "args": ["GroupDocs.Watermark.Mcp", "--yes"],
      "env": {
        "GROUPDOCS_MCP_STORAGE_PATH": "/path/to/documents"
      }
    }
  }
}