mitmproxy MCP Server

A Model Context Protocol (MCP) server that transforms mitmproxy into a powerful toolset for AI agents. This allows LLMs (like Claude, GPT-4, or local models) to inspect, modify, and replay HTTP/HTTPS traffic in real-time.

New in this build (the fun stuff)

This project has grown beyond simple capture + replay. You can now:

• Search traffic quickly with filters by domain/method/body text.
• Extract data from responses using JSONPath or CSS selectors.
• Use session variables to grab tokens from one response and reuse them in later replays.
• Run lightweight fuzzing against query params or JSON body fields for quick DAST checks.
• Reconstruct API patterns and export an OpenAPI-style spec from captured traffic.
• Detect auth patterns (Bearer/JWT/API key/session cookie/CSRF/OAuth hints).
• Generate starter scraper code from real captured flows.

Why use this?

Standard "web search" or "fetch" tools are stateless and easily detected. mitmproxy-mcp provides:

• Deep Debugging: The agent can inspect full request/response cycles (headers, payloads, cookies) to identify why a frontend is failing or why an API is returning a 4xx/500 error.
• API Reverse Engineering: Let the LLM observe undocumented internal APIs, map out JSON schemas, and generate client libraries or documentation automatically.
• Automated Security Testing: Perform DAST (Dynamic Application Security Testing) by allowing the agent to inject payloads into specific parameters and analyze the response.
• Live Interception: Modify traffic on the fly: inject headers, mock responses for testing, or block tracking pixels to reduce noise.
• Stealth Replay: Uses curl-cffi to mimic Chrome/Safari TLS fingerprints, bypassing basic anti-bot measures that standard Python libraries trigger.

Key Features

• Lifecycle Control: Start and stop the mitmproxy instance directly from the LLM.
• Deep Inspection: Capture full request/response cycles, including headers, bodies, and timing.
• Traffic Search & Filtering: Scope by domain, then search flows by query/method so context stays clean.
• Active Interception: Dynamic rules to inject headers, replace body content via regex, or block requests.
• Stealth Replay: Re-execute flows using curl-cffi to impersonate modern browser TLS fingerprints (e.g., Chrome).
• Session-Aware Workflows: Extract dynamic values (like CSRF tokens) and re-inject them into replayed traffic.
• Response Data Extraction: Pull structured values from HTML/JSON responses via CSS selectors and JSONPath.
• API Discovery: Group similar endpoints, identify path/query params, and export OpenAPI JSON.
• Security Recon Helpers: Detect common auth patterns and run targeted fuzz payloads.
• Scraper Bootstrapping: Generate executable curl-cffi automation code from observed traffic.

Quickstart

Option 1: Using uvx (Recommended)

Add this to your MCP client configuration (e.g., Claude Desktop, Cursor, or AntiGravity):

{
  "mcpServers": {
    "mitmproxy-mcp": {
      "command": "uvx",
      "args": ["mitmproxy-mcp"]
    }
  }
}

Installation

Option 1: Global Install (with uv)

uv tool install mitmproxy-mcp

Option 2: Docker (Isolated Environment)

# Build and run
docker build -t mitmproxy-mcp .
docker run -p 8080:8080 mitmproxy-mcp

Option 3: Manual Pip Install

python -m venv venv
source venv/bin/activate
pip install mitmproxy-mcp

Available Tools

Lifecycle & Configuration

• start_proxy(port=8080): Starts the mitmproxy server.
• stop_proxy(): Shuts down the proxy.
• set_scope(allowed_domains): Filters recorded traffic (e.g., ["api.github.com", "example.com"]).
• list_tools(): Returns all exposed MCP tools and input schemas.

Inspection

• get_traffic_summary(limit=20): Returns a list of recent network flows.
• inspect_flow(flow_id): Provides full details and a curl equivalent for a specific flow.
• search_traffic(query, domain, method, limit=50): Filter captured traffic by keyword/domain/method.
• clear_traffic(): Clears persisted traffic history.

Modification & Interception

• add_interception_rule(rule_id, action_type, ...):
• action_type: inject_header, replace_body, or block.
• phase: request or response.
• set_global_header(key, value): Injects a header into every request.
• remove_global_header(key): Removes a previously injected global header.
• list_rules(): Shows currently active interception rules.
• clear_rules(): Flushes all active interception rules.

Replay

• replay_flow(flow_id, method, headers_json, body): Re-sends a request with modifications using browser-grade impersonation.

Extraction & Session Variables

• extract_from_flow(flow_id, json_path=None, css_selector=None): Extract values from captured response bodies.
• set_session_variable(name, value): Manually set a session variable.
• extract_session_variable(name, flow_id, regex_pattern, group_index=1): Extract and save a variable from a response body.

Security & API Analysis

• fuzz_endpoint(flow_id, target_param, param_type, payload_category, timeout=10.0): Replay with payload substitutions and report anomalies.
• get_api_patterns(domain=None, limit=50): Cluster captured traffic into endpoint patterns.
• export_openapi_spec(domain=None, limit=50): Produce an OpenAPI v3 JSON spec from captured traffic.
• detect_auth_pattern(flow_ids=None): Infer likely auth mechanisms from observed requests.

Code Generation

• generate_scraper_code(flow_ids, target_framework="curl_cffi"): Generate starter scraper/automation code from captured flows.

Programmatic Usage

Note: These are JSON-RPC calls sent by the MCP Host (Client). You do not need to type these manually in the terminal.

1. Initialize the Proxy: {"method": "tools/call", "params": {"name": "start_proxy", "arguments": {"port": 8080}}}
2. Intercept & Block: {"method": "tools/call", "params": {"name": "add_interception_rule", "arguments": {"rule_id": "block-ads", "action_type": "block", "url_pattern": ".*analytics.*"}}}
3. Modify Response: {"method": "tools/call", "params": {"name": "add_interception_rule", "arguments": {"rule_id": "mock-api", "action_type": "replace_body", "url_pattern": ".*user/profile.*", "action_value": "{\"name\": \"AI Agent\"}"}}}

Helpful Tips

• Manage Context: Use set_scope immediately. LLMs perform poorly when flooded with background OS telemetry.
• Browser Setup: Ensure your browser or application is configured to use the proxy (usually localhost:8080) and has the mitmproxy CA certificates installed for HTTPS inspection.
• Stealth: The replay_flow tool uses curl-cffi specifically to avoid being flagged as a bot by services that check TLS fingerprints.

Development

git clone [https://github.com/snapspecter/mitmproxy-mcp.git](https://github.com/snapspecter/mitmproxy-mcp.git)
cd mitmproxy-mcp
uv sync
uv run pytest

License: MIT

Author: SnapSpecter