Finally, a cross-platform HTTP debugger without time and feature restrictions

The world of HTTP debugger is filled with paid tools.

You've probably need to use at some point software like Fiddler, Charles, Burp, etc. Theses tools are great and may have some advantages and drawbacks in some ways but they share one thing in common: you must pay at some point to access all features or to be able to use it on a different platforms/OS.

We built Fluxzy Desktop to be forever free, unlimited, and fully-featured for indie devs and individuals. Unlike several HTTP debuggers, Fluxzy provides all offline Fluxzy features included in the Community Edition without any time limitation.

Features like breakpoints, live editing, mocking (in every way) load and record traffic, and more are usually only available in paid versions of other tools and available for free in Fluxzy Desktop with a first-class accessibility.

Actually Fluxzy Desktop is build upon the Fluxzy.Core library, which is completely open-source, and includes exhaustively all the necessary all offline features used by the desktop application.

So what make this software different?

There are a few original ideas that is embedded in Fluxzy Desktop we didn't find in other tools. If you are too lazy to browse this website, here's is a quick overview of what makes Fluxzy Desktop different from other tools:

Out-of-the-box PCAP support

Fluxzy provides a very simple way to capture raw packets alongside HTTP data in a deciphered format across any platform in a consistent way.

PCAP data are a must-have to diagnose network-related issues; however, it's not enough for application layer developers as getting simple information like a URL path is quite hard when TLS is on. Fluxzy combines the best of both worlds and offers it in two ways: the fluxzy archive, which contains both HTTP level data and raw packets. PCAPNG file can be extracted from this archive and contains only the transport related packets without any noise.

Additionally, if you choose to use the Bouncy Castle SSL Engine during the capture session, decryption keys are automatically saved within the PCAPNG file, allowing you view the TLS traffic in plain with Wireshark with no additional configuration.

Declarative traffic alteration

Most tools will provide you a scripting language (usually js) to apply custom traffic alteration. It's fine but it requires you to write code to apply traffic modification. Moreover, it's significantly slower because the script has to be interpreted at runtime.

With Fluxzy, traffic alteration and manipulation can be done purely with a simple UI. The resulting configuration can be exported later to a YAML file and used with the CLI, the docker image, or the .NET library.

There are already several dozen of custom directives you can use from adding simple headers to complex rules like injecting <script/> on processing HTML pages.

For example, the following YAML config will make any html page background red:

- filter:
    typeKind: AnyFilter
  - typeKind: InjectHtmlTagAction
    tag: head
    htmlContent: '<style>body { background-color: red !important; }</style>'
    restrictToHtml: true

Designed for observability

Fluxzy was designed to be the least intrusive as possible and deliver the smoothest synthetic monitoring experience. We have ensured that the core pipeline process and any built-in directives are fully streamed to produce minimal latency and to guarantee predictable memory usage regardless of the traffic volume.

Moreover, we brought performance insight to Fluxzy Desktop to help you quickly isolate exchanges having performance bottlenecks and get statistics on exchanges by latency, size, and more.

Is this tool Open Source?

The core library containing all debugging features (include breakpoints) is already open-source. The front UI just wraps the core library to deliver UI Experience for desktop users.

Give it a try

Fluxzy is under constant development, with new features and improvements being added weekly. We strive to keep Fluxzy evolving to meet the dynamic needs of the developer community. We are always open to feedback and suggestions, so feel free to reach out to us with your ideas.