HAR MCP Server

An MCP (Model Context Protocol) server for analyzing HAR (HTTP Archive) files with LLM-friendly output.

Runtime Requirement: This server requires Bun >= 1.0.0.

Features

• Multiple analysis modes: summary, list, detail, content, stats, timeline, size, cookies
• Powerful filtering: URL patterns, HTTP methods, status codes, content types, duration, body content
• Sorting & pagination: Sort by various fields, paginate large result sets
• Export capabilities: Export entries as cURL commands
• JSON output: Programmatic JSON output for integration
• Chrome DevTools support: Full support for Chrome-exported HAR files with extension fields
• Truncated HAR repair: Automatic recovery of truncated HAR files (common with large exports)

Installation

bun install

This server only supports Bun runtime.

Usage

With Claude Desktop

After installing from npm, use bunx:

{
  "mcpServers": {
    "har": {
      "command": "bunx",
      "args": ["har-mcp"]
    }
  }
}

For local development:

{
  "mcpServers": {
    "har": {
      "command": "bun",
      "args": ["run", "/path/to/har-mcp/src/index.ts"]
    }
  }
}

With OpenCode

After installing from npm, use bunx:

{
  "mcp": {
    "servers": {
      "har": {
        "type": "local",
        "command": ["bunx", "har-mcp"]
      }
    }
  }
}

For local development:

{
  "mcp": {
    "servers": {
      "har": {
        "type": "local",
        "command": ["bun", "run", "/path/to/har-mcp/src/index.ts"]
      }
    }
  }
}

With MCP Inspector

npx @modelcontextprotocol/inspector bun run src/index.ts

Tools

read_har

Reads and analyzes HAR files with multiple output modes.

Parameters:

| Parameter | Type | Description | | ---------- | -------- | ---------------------------------------------------------- | | path | string | Required. Path to the HAR file | | mode | string | Output mode (default: "summary") | | filter | object | Filter criteria | | sort | object | Sorting options | | page | number | Page number for pagination (default: 1) | | pageSize | number | Entries per page (default: 20, max: 100) | | entries | number[] | Specific entry indexes (required for content/detail modes) | | format | string | Output format: "markdown" or "json" |

Output Modes:

| Mode | Description | | ---------- | ------------------------------------------------------------------ | | summary | Overview statistics (total entries, methods, status codes, timing) | | list | Paginated entry list with basic info | | detail | Full metadata for specific entries (headers, timing, query params) | | content | Response/request bodies for specific entries | | stats | Aggregate statistics grouped by endpoint | | timeline | Text-based waterfall visualization | | size | Payload size analysis | | cookies | Cookie propagation tracking |

Filter Options:

| Filter | Type | Description | | -------------- | -------------------------- | --------------------------------------------------------- | | url | string | URL pattern (substring, glob with *, or ~regex) | | method | string | string[] | HTTP method(s) to filter | | status | number | string | object | Status code, pattern (e.g., "4xx"), or range {min, max} | | contentType | string | Response content type filter | | minDuration | number | Minimum request duration in ms | | hasError | boolean | Filter to errors only (4xx/5xx) | | bodyContains | string | Filter by response body content |

Sort Options:

| Field | Description | | ---------- | -------------------------- | | index | Original order in HAR file | | time | Request start time | | duration | Request duration | | size | Response size | | status | HTTP status code |

Examples:

// Get summary of a HAR file
read_har(path: "/path/to/file.har")

// List all POST requests
read_har(path: "...", mode: "list", filter: { method: "POST" })

// Find slow requests (over 1 second)
read_har(path: "...", mode: "list", filter: { minDuration: 1000 }, sort: { by: "duration", order: "desc" })

// Get response body for first two entries
read_har(path: "...", mode: "content", entries: [0, 1])

// Find requests matching URL pattern
read_har(path: "...", mode: "list", filter: { url: "*/api/*" })

// Filter by regex
read_har(path: "...", mode: "list", filter: { url: "~\\.json$" })

// Find errors
read_har(path: "...", mode: "list", filter: { hasError: true })

// Filter by status range
read_har(path: "...", mode: "list", filter: { status: { min: 400, max: 499 } })

// Analyze request sizes
read_har(path: "...", mode: "size")

// View timeline waterfall
read_har(path: "...", mode: "timeline")

// Track cookies
read_har(path: "...", mode: "cookies")

// Get JSON output
read_har(path: "...", mode: "summary", format: "json")

export_har_curl

Export HAR entries as cURL commands for replay or debugging.

Parameters:

| Parameter | Type | Description | | ---------------- | -------- | --------------------------------------- | | path | string | Required. Path to the HAR file | | entries | number[] | Required. Entry indexes to export | | includeHeaders | boolean | Include request headers (default: true) | | includeCookies | boolean | Include cookies (default: false) | | compressed | boolean | Add --compressed flag | | verbose | boolean | Add -v flag |

Example:

// Export first request as cURL
export_har_curl(path: "/path/to/file.har", entries: [0])

// Export with cookies and verbose output
export_har_curl(path: "...", entries: [0, 1], includeCookies: true, verbose: true)

Browser Compatibility

This MCP server fully supports HAR files exported from:

• Chrome DevTools - Including all Chrome-specific extension fields (_initiator, _priority, _resourceType, _transferSize, _workerRespondWithSettled, etc.)
• Firefox DevTools - Standard HAR 1.2 format
• Safari Web Inspector - Standard HAR format
• Other tools - Any HAR 1.2 compliant export

Truncated HAR Repair

Large HAR files exported from browsers can sometimes be truncated (incomplete JSON). This server automatically detects and repairs truncated HAR files by:

1. Finding the last complete HTTP entry
2. Reconstructing valid JSON structure
3. Displaying a warning with the number of recovered entries

When a truncated file is repaired, you'll see a warning like:

⚠️ **Warning**: HAR file was truncated and has been repaired.
Recovered 182 entries using chrome-timings repair method.
Some entries at the end of the file may be missing.

Development

bun start        # Run the server
bun test         # Run tests
bun lint         # Check code style
bun format       # Format code

Project Structure

src/
├── index.ts          # Entry point - stdio transport setup
├── server.ts         # MCP server configuration and tool registration
└── tools/
    └── har/
        ├── index.ts  # Tool exports and registration
        ├── schema.ts # Zod schemas for input validation
        └── modes/    # Output mode implementations

License

MIT