fluxzy is a versatile HTTP intermediate and Man-In-The-Middle proxy for recording, analyzing, debugging, and altering HTTP/1.1, H2, WebSocket traffic over plain or secure channels.

fluxzy was build to produce precise performance indicators for various observability scenarios. To this end, and unlike most MITM tool, fluxzy provides full request/response streaming in every stage of the HTTP exchange including built-in active alteration actions.

You can use it as:

  • A desktop application, named Fluxzy Desktop available on Windows, macOS and linux.
  • A command line tool, named Fluxzy CLI (command fluxzy), for starting a new capture session, managing certificates, reading a fluxzy archive and directory and exporting fluxzy outputs to other formats.
  • .NET package named Fluxzy.Core available on nuget.org. You can find this project on Github.

Download & Install

Visit the download page page to get the latest stable for your platform.


Core Features

Find below a non-exhaustive list of Fluxzy capabilities and features shared across all Fluxzy products:

Feature Desktop CLI Core Comment
Supports HTTP/1.1, HTTP/2, and Web Sockets
Inspects traffic in clear
Deflects OS traffic to Fluxzy
Act as system proxy
Automatic ROOT CA installation
Use a custom root certificate
Save and load captured HTTP exchanges
Save and load filters and actions
Replay captured HTTP exchanges
Run and hook browsers and terminals
Live edit
Halt ongoing exchanges and edit requests and responses on the fly
Export and import HAR files
Export and import SAZ files (experimental)
Export exchange to cURL command for Bash and cmd
Codeless traffic alteration
Dual SSL engine
Choice between the OS default engine (SChannel for Windows, OpenSSL for Linux)
Capture raw network packets Needs elevation
Capture NSS Key logs with raw network packets Available when using Bouncy castle engine
Store NSS Keys with SSLKEYLOGFILE format Available when using Bouncy castle engine
Custom filter builder, including multiple filter combinations
Metadata support: comments and tags
Precise traffic measurements including transport-level timings
Multipart data viewer: retrieve an upload file in the exchange

Traffic Processing Features

Traffic Processing features are handled by filters and action directives.

You can use the search engine built on this page to list all available filters and actions on the latest stable version.

  • Add, remove, modify request and response headers
  • Change request method, path
  • Alter request and response body
  • Mock request body (file, immediate text, ..)
  • Mock response body (file, immediate text, ..)
  • Forward requests
  • Search in every part of request
  • Spoof DNS
  • Add client certificate (mutual TLS)
  • Force HTTP version
  • Force SSL/TLS version
  • Simulate failures
  • Extract variables from exchanges and reuse them
  • Write to stdout and to file on the fly