Fluxzy Desktop is a free HTTP debugging proxy for developers who need to see what's actually happening on the wire.
The problem we all know too well
You're debugging an API integration. Something's wrong. You fire up your trusty proxy tool and... wait, why isn't HTTP/2 working? Why can't you see that WebSocket traffic? Why does exporting to Wireshark feel like performing surgery with a spoon?
Legacy debugging tools were built when HTTP/1.1 was cutting edge and TLS was optional. We're not in that world anymore.
What Fluxzy actually does
Capture, inspect, and modify HTTP/HTTPS traffic across HTTP/1.1, HTTP/2, and WebSocket. Set breakpoints to pause requests mid-flight and edit them before they continue. Mock API responses without touching your backend. Throttle bandwidth to simulate that 3G connection your users are definitely still on.
The rule engine uses composable YAML—version control your debugging setup, share it with your team, run the exact same rules in CI. No more "works on my machine" for network behavior.
The stuff nobody else does
Native PCAP capture built in. Not "export and pray"—actual packet-level recording alongside your HTTP traffic. When you need to know if that latency is TLS negotiation or server response time, you'll have the data.
Custom TLS fingerprinting via BouncyCastle. Some servers detect and block proxies based on their TLS signature. Fluxzy can impersonate real browser fingerprints when you need to see what actual users see.
Full-text search across every request and response. Filter by process name to isolate just your app's traffic. Compare any two exchanges side-by-side with proper diff highlighting.
Built for how you actually work
Launch browsers with proxy pre-configured—no manual proxy settings. Export to HAR, SAZ (Fiddler format), cURL, or .http files. Import captures from other tools.
Works on Windows, macOS, and Linux. The CLI version runs headless for automation and monitoring. Same engine, same rules, same results.
Completely free for personal use
Fluxzy Desktop is freeware with no feature restrictions for individual developers. The core engine (Fluxzy.Core) is fully open source—audit the code, extend it, trust it.
Professional licensing available for workplace use.
Try it
Download at fluxzy.io. No account required. No trial period. Just a debugging tool that respects your time.
Screenshots
Product Updates (0)
No updates yet. Check back later for updates from the team.
Hey! I built Fluxzy because Fiddler went subscription and I didn't want to pay monthly for something that runs on my own machine.
Fluxzy is:
100% offline (no accounts, no cloud)
Free for personal use
Comments (3)
Congrats on the launch!
wow 🚀
Hey! I built Fluxzy because Fiddler went subscription and I didn't want to pay monthly for something that runs on my own machine. Fluxzy is: 100% offline (no accounts, no cloud) Free for personal use