HAR MCP Server

HAR MCP Server

A Model Context Protocol (MCP) server for parsing and analyzing HAR (HTTP Archive) files. This server allows AI assistants to inspect network traffic captured in HAR format, with built-in support for redacting sensitive authentication headers.

Features

• Load HAR files from local filesystem or HTTP URLs
• List all URLs and HTTP methods accessed in the HAR file
• Query request IDs for specific URL and method combinations
• Retrieve full request details with automatic redaction of authentication headers
• Flexible HAR parsing that handles real-world HAR files with:
  • Float/decimal values for time fields (automatically rounded to integers)
  • Plain text or base64-encoded response content
  • Additional fields not present in the basic HAR spec
• Support for standard HAR format as produced by browser developer tools

Installation

You can install this MCP server using your standard MCP configuration.

Add the following JSON block to your mcp configuration.

Using docker

{
  "mcp": {
    "servers": {
      "har": {
        "command": "docker",
        "args": [
          "run",
          "-i",
          "--rm",
          "ghcr.io/tjamet/har-mcp"
        ]
      }
    }
  }
}

Using go run

Alternatively you can run thr server directly with go run.

{
  "mcpServers": {
    "github": {
      "command": "go",
      "args": [
        "run",
        "github.com/tjamet/har-mcp/cmd/har-mcp@main"
      ]
    }
  }
}

Build from source

If you don't have Docker, you can use go build to build the binary in the cmd/har-mcp directory, and use the github-mcp-server command. To specify the output location of the build, use the -o flag. You should configure your server to use the built executable as its command. For example:

{
  "mcp": {
    "servers": {
      "github": {
        "command": "/path/to/har-mcp-server"
      }
    }
  }
}

Usage

The HAR MCP server runs as a stdio-based MCP server, communicating via JSON-RPC over standard input/output.

Running the Server

./har-mcp

Available Tools

1. load_har

Load a HAR file from a file path or HTTP URL.

Parameters:

• source (string, required): File path or HTTP URL to the HAR file

Example:

{
  "source": "/path/to/capture.har"
}

2. list_urls_methods

List all accessed URLs and their HTTP methods from the loaded HAR file.

Parameters: None

Returns: Array of URL/method combinations with their associated request IDs.

3. get_request_ids

Get all request IDs for a specific URL and HTTP method.

Parameters:

• url (string, required): The URL to filter by
• method (string, required): The HTTP method to filter by (GET, POST, etc.)

Example:

{
  "url": "https://api.example.com/users",
  "method": "GET"
}

4. get_request_details

Get full request details by request ID. Authentication headers will be automatically redacted.

Parameters:

• request_id (string, required): The request ID to retrieve details for

Example:

{
  "request_id": "request_0"
}

Redacted Headers:

• Authorization
• X-API-Key
• X-Auth-Token
• Cookie
• Set-Cookie
• Proxy-Authorization

Integration with Claude Desktop

Add the following to your Claude Desktop configuration:

{
  "mcpServers": {
    "har-mcp": {
      "command": "/path/to/har-mcp"
    }
  }
}

Development

Running Tests

go test ./...

Project Structure

.
├── cmd/
│   └── har-mcp/       # Main application
│       └── main.go
├── pkg/
│   └── har/           # HAR parsing library
│       ├── parser.go
│       └── parser_test.go
├── go.mod
├── go.sum
└── README.md

Dependencies

• github.com/google/martian/har - HAR file parsing
• github.com/mark3labs/mcp-go - MCP server implementation
• github.com/stretchr/testify - Testing assertions

License

[Add your license here]