mitmproxy

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Introduction

mitmproxy is an interactive, SSL/TLS-capable intercepting proxy with a console interface for HTTP/1, HTTP/2 and WebSockets. mitmdump is its command-line version (“think tcpdump for HTTP”) and mitmweb is a web-based interface. The project is MIT-licensed with about 46,800 GitHub stars.

An intercepting proxy sits between a client and a server so you can see, modify and replay traffic. Security testers use it to inspect API calls from mobile and web apps, tamper with requests and check how servers respond; developers use it to debug integrations.

mitmproxy is scriptable in Python through addons, which makes it useful for automated testing too: you can rewrite responses, inject faults, record traffic or assert on requests in CI.

In the quality loop it supports security testing and API debugging, and it is often used to build test fixtures from real traffic.

Features

1. Interactive console: Inspect and edit flows in a terminal UI.
2. mitmweb: Browser-based interface.
3. mitmdump: Command-line capture, filtering and scripting.
4. TLS interception: Decrypt HTTPS with a locally trusted certificate.
5. HTTP/2 and WebSockets: Modern protocol support.
6. Python addons: Script request and response handling.
7. Replay: Client and server-side replay of recorded flows.
8. Modes: Regular, transparent, reverse and other proxy modes; see the docs.

Pros

1. Free and open: MIT.
2. Scriptable: Python addons for automation.
3. Three interfaces: Console, web and CLI.
4. Very popular: Large community and documentation.
5. Active: Commits in November 2026.

Cons

1. Certificate setup: Clients must trust the mitmproxy CA; pinned apps resist interception.
2. Not a scanner: No automated vulnerability scanning like ZAP or Burp’s scanner.
3. Console learning curve: Keyboard-driven UI takes practice.
4. Authorised use only: Intercept only traffic you are allowed to inspect.
5. Performance: Not built for high-throughput production proxying.

Usage and Links (Example)

Start the web interface and point your client’s proxy at it (port 8080 by default):

mitmweb

Rewrite a response header with an addon:

# addon.py
def response(flow):
    flow.response.headers["x-tested-by"] = "mitmproxy"

mitmdump -s addon.py

Tips: install the mitmproxy CA only on test devices, save flows for reproducible bug reports, and use addons to inject errors and latency when testing client resilience.

Resources:

• mitmproxy website
• Documentation
• GitHub repository

Pricing

mitmproxy is free and open source under MIT.

Recommended for?

1. Security testers inspecting and tampering with app traffic.
2. Mobile and API developers debugging requests.
3. QA engineers injecting faults through scripted proxies.
4. Not a fit if you need an automated vulnerability scanner.

Conclusion

mitmproxy is the go-to open-source intercepting proxy, with three interfaces and Python scripting.

Use it on authorised traffic, and pair it with scanners such as ZAP or Burp for automated checks.