The Neighbours

mitmproxy is not the only seat from which traffic can be watched, and several of its neighbours see things it cannot. An honest map:

The browser's developer tools

Every desktop browser carries a Network panel: the requests that page made, with headers, timing and previews, one click from the page itself. For pure web page debugging this is often the right tool — no proxy to configure, no CA to trust, and it sees the browser's own view (cache hits, service workers) that a proxy never can. Its limits are its walls: one browser, one profile, no other programs, and nothing saved in a form you can script against afterwards. mitmproxy is the answer when the client is not a browser, or when the recording must outlive the session.

Wireshark and tcpdump

The packet tools (this series has a Wireshark guide) watch the wire itself: every packet, every protocol, whether or not the traffic was addressed to them. They see what mitmproxy structurally cannot — DNS lookups, the TLS handshake in its armour, protocols that are not HTTP at all, traffic from programs that ignore proxy settings entirely. What they cannot easily give you is the conversation: HTTPS in Wireshark is ciphertext unless you feed it session keys, and a request's body is an exercise in reassembly. The tools are complements, not rivals: packets to prove where bytes went, a proxy to read what the bytes said.

Charles Proxy

The long-standing commercial neighbour on macOS and Windows: a polished GUI proxy with throttling, breakpoints and repeat-request tools that clearly taught the species its manners. If a team already licenses it and lives in its UI, it does the chapter-1-to-9 jobs well. mitmproxy's counter-offer is being open source, scriptable in Python end to end, and at home in a terminal and a CI job.

Fiddler

The Windows classic, now cross-platform as Fiddler Everywhere: HTTPS interception with an approachable interface and a session list generations of developers learned on. Its auto-responder is server replay (chapter 10) with good tailoring. The trade against mitmproxy is the same shape as Charles': a product with a licence and a UI, versus a tool with a scripting engine and a command line.

Burp Suite

The security professional's proxy: an interception core surrounded by a scanner, an intruder (automated attack) tool, and two decades of web-testing craft. If your job is assessing other systems' security — with a contract that says so — Burp is the trade's standard and this guide is no substitute. For watching your own traffic and learning, it is a siege engine brought to open a letter. Chapter 1's rule is the difference between the two books that could be written about either tool.

A plain HTTP echo and logging

Sometimes the neighbour is smaller: an echo service (the lab's is mitmproxy-lab/server/), a server's own access log, a curl -v. Half of debugging is asking the traffic a yes/no question, and those need a yes/no tool. Reach for the proxy when the question is show me the conversation; reach for the small tools when it is did it arrive at all.