mitmproxy Alternative - A Modern HTTP Debugging Proxy

Looking for a mitmproxy alternative that fits your workflow?

mitmproxy is a remarkable project. It is fully open source, scriptable to the bone, and its protocol coverage is among the best in the field. If you live in a terminal and think in Python, it may already be the right tool for you. But if you want a real desktop application, traffic rules you can build without writing code, and visibility below the HTTP layer, that is where Fluxzy comes in.

Download Fluxzy Desktop - Free

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Different tools fit different needs. Here is what we hear from developers who use mitmproxy but want something else for day-to-day debugging.

There is no native desktop app. mitmproxy gives you a terminal UI (mitmproxy), a browser-based UI (mitmweb), and a headless CLI (mitmdump). All three are capable, but none of them is a first-class desktop application. For long interactive debugging sessions, many developers want proper windows, panes, keyboard-and-mouse ergonomics, and a UI that keeps state across sessions.

Everything beyond the basics is Python. mitmproxy's power comes from its addon API, and that is also its tax. Rewriting traffic, mocking endpoints, or automating a scenario quickly means writing and maintaining Python scripts. That is great for engineers who want a programmable proxy, and heavy for anyone who just wants to change a header, mock a response, and get back to work.

It stops at the flow level. mitmproxy shows you flows: requests, responses, messages. It can log TLS keys, but it does not capture raw packets, it cannot export a session to Wireshark on its own, and the TLS signature it presents to servers is its own. When a problem lives in the handshake, the retransmissions, or the fingerprint, you reach for a second tool.

If you want a native GUI, no-code traffic rules, packet-level capture, and TLS fingerprint control, that is where Fluxzy comes in.

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Here is how the two tools compare across key capabilities:

Capability	mitmproxy	Fluxzy Desktop
Price	Free, open source (MIT)	Free for personal use
Interface	Terminal UI, browser UI (mitmweb), headless CLI	Native desktop app (Tauri) plus full CLI
Open Source	✅ Entire tool	✅ Core engine (Fluxzy.Core)
Platforms	Windows, macOS, Linux	Windows, macOS, Linux
HTTP/2 Support	✅ Yes	✅ Yes
HTTP/3 Support	✅ Yes	🔄 Coming soon
WebSocket	✅ Yes	✅ Yes
gRPC	⚠️ Protobuf prettify	✅ Decoded directly
Breakpoints	✅ Intercept in TUI or browser	✅ Multi-level, visual
Traffic Rules	CLI options and Python addons	YAML or visual editor, composable, no code
Scripting Language	Python	Declarative YAML, or .NET for deep cases
Transparent / Proxyless Capture	✅ Yes (local, transparent, WireGuard modes)	✅ Preview (Windows, macOS, Linux)
Raw Packet Capture (PCAP)	❌ No	✅ Native support
Wireshark Export	⚠️ TLS key logging only, packets need a second tool	✅ Yes (PCAPNG + NSS keys)
TLS Fingerprinting	❌ No (presents its own signature)	✅ Yes (client impersonation)
LLM API Decoding (OpenAI, Anthropic)	❌ No	✅ Yes
Runtime	Python	Rust shell with a compiled .NET core

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mitmproxy's interactive console is efficient once you learn its keystrokes, and mitmweb covers the basics in a browser tab. Fluxzy Desktop is a full native-feeling application built on Tauri: a persistent workspace with a traffic grid, detail panes, visual filters, a rule editor, and breakpoint dialogs. No terminal multiplexer, no browser tab that loses your layout, no keybinding cheat sheet on your second monitor.

In mitmproxy, simple jobs have flags (map_local, map_remote, modify_headers) and everything else becomes an addon script. Fluxzy folds all of it into one composable rule engine with 50+ actions:

• Add, update, or remove headers
• Inject authentication (Basic, Bearer)
• Mock responses with custom status codes and bodies
• Serve local files instead of remote content
• Redirect requests to another host
• Spoof DNS
• Add delays and throttle bandwidth
• Inject HTML or JavaScript into pages

Every rule can be built in the visual editor or written directly as YAML, and the two are interchangeable. You get the "configuration as text" property that makes mitmproxy scripts shareable and versionable, without maintaining code. And when a case genuinely needs programming, the open-source .NET core gives you a full API.

mitmproxy works at the flow level. It can write TLS keys to an SSLKEYLOGFILE, but it does not capture the packets those keys decrypt, so diagnosing anything below HTTP means running a packet capture tool alongside it and lining up two timelines by hand.

Fluxzy collapses that into one session. It operates at the HTTP, transport, and TLS layers at the same time. Native PCAP capture exports straight to Wireshark, and with NSS key logging you get fully decrypted TLS alongside packet-level timing, retransmissions, and handshake detail, right next to the HTTP view.

When mitmproxy sits in the middle, servers see the TLS signature of its Python stack, and fingerprint-based detection (JA3 and friends) can spot it. There is no built-in way to change what it presents. If the server alters its behavior because it detects a proxy, your test results quietly stop matching reality.

Fluxzy lets you control that fingerprint. Using BouncyCastle alongside the native .NET TLS stack, it can reproduce the cryptographic handshake of a specific client, so the server on the far end sees the client you are impersonating rather than the tool in the middle.

mitmproxy automates well: mitmdump runs headless and your addons travel with it. Fluxzy gives you the same property without the code. The exact rules you build in the desktop app, visually, while debugging, are the exact YAML that Fluxzy CLI runs:

• Capture and shape traffic interactively in the desktop app
• Export the rule set to YAML
• Run that identical YAML headless in CI/CD
• Drop it into a Docker container
• Reuse it across an automated test suite

Your debugging session and your automation are the same artifact, and nobody on the team has to read Python to review a rule change.

HTTP/1.1, HTTP/2, and WebSocket are captured with full detail, individual HTTP/2 streams and WebSocket frames included. gRPC is decoded directly rather than prettified as raw Protobuf. And OpenAI and Anthropic chat completion calls are parsed natively, including streamed responses, which is handy when debugging AI agents. mitmproxy is ahead on HTTP/3 today; Fluxzy's HTTP/3 support is on the way.

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If you know mitmproxy, you already know the jobs you want to do. Here is how each one is handled in Fluxzy.

mitmproxy uses filter expressions (~u, ~d, ~m and friends). Fluxzy uses a composable filter system with 50+ filter types: host, path, method, status code, headers, cookies, content type, process name, and more, combined with AND/OR logic and saved as reusable presets. The same filters that scope what you see also scope which rules fire.

mitmproxy's intercept pauses matching flows for editing in the console or browser UI. Fluxzy does the same with visual breakpoints, in the free version, and multi-level breakpoints let you stop at both the request and the response stage of the same exchange, then modify, continue, or abort.

Each mitmproxy option or addon maps to an action in the Fluxzy rule engine: serve local files, redirect to another host, rewrite headers and bodies, mock full responses, throttle, spoof DNS. Compose them freely, edit them visually or as YAML.

Both run headless. The difference is what travels: with mitmdump you carry Python addons, with Fluxzy CLI you carry the same declarative YAML the desktop app produced.

Most rewriting jobs need no code at all in Fluxzy. For the cases that do, Fluxzy.Core is an open-source .NET library you can embed, extend, and audit, the same engine the desktop app and CLI run on.

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Fluxzy does not read mitmproxy's native flow files directly, but it imports HAR. mitmproxy can export flows to HAR, so the path across is simple: export from mitmproxy, import into Fluxzy, and keep working.

The mental model carries over directly. Flows become a traffic grid. Filter expressions become composable visual filters. Intercept becomes breakpoints. Options and addons become rules.

A native app instead of a console. Persistent layout, visual editing, and mouse-friendly inspection, with a full CLI still there when you want it.

Rules instead of scripts. Declarative YAML you can review in a pull request without knowing Python, interchangeable with a visual editor.

Deeper than flows. Packet-level capture, Wireshark export with decryption keys, and TLS negotiation detail alongside the HTTP view.

A fingerprint you control. Impersonate a real client's TLS handshake instead of presenting a detectable proxy signature.

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Fluxzy Desktop is fully featured and free for hobbyists and individual developers, with paid licenses for professional and workplace use funding development. mitmproxy is free for everyone under the MIT license, so if license cost is your only criterion, mitmproxy already has you covered. What Fluxzy's model buys is a polished native desktop experience on top of an open-source core.

For interactive HTTP debugging (inspection, interception, rewriting, mocking, throttling, DNS spoofing, headless automation), yes, and without writing Python. mitmproxy keeps real advantages: it is entirely open source, it supports HTTP/3 today, it proxies raw TCP and UDP, and modes like WireGuard have no Fluxzy equivalent. If those are central to your work, mitmproxy remains an excellent choice, and the two tools coexist happily.

The core engine (Fluxzy.Core) is open source and available on GitHub, so you can audit every interception mechanism, every cryptographic decision, every stream transformation. The desktop app is freeware built on top of that open core. mitmproxy is open source end to end, including its UIs.

Fluxzy does not open mitmproxy flow files directly, but it imports HAR. Export your flows from mitmproxy as HAR, then import them into Fluxzy.

Yes, as a first-class platform. Fluxzy ships the same native app with the same features on Windows, macOS, and Linux, including transparent capture in preview on all three.

You can capture plain HTTP without any certificate. To read HTTPS traffic in clear text you install and trust the Fluxzy root certificate, exactly as you install and trust the mitmproxy CA certificate today (for example via mitm.it). The mechanism is identical, only the tool changes.

Yes, this is a first-class use case. Fluxzy CLI uses the exact same engine as the desktop app. Define rules in YAML, run them headless in CI/CD. Capture traffic in containers. Generate PCAP files for analysis. If you automate with mitmdump today, the workflow will feel familiar, minus the addon code.

If you are weighing GUI proxies against each other, we cover those comparisons in detail on the Fiddler alternative page, the Charles alternative page, and the Proxyman alternative page.

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Download Fluxzy Desktop

Available for Windows, macOS, and Linux. Free forever for personal use.

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• Documentation: Full user guide and reference
• GitHub: Open source core engine

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Built for modern development workflows. Give it a try and see if it fits.