HTTP debugger features

See why people are switching to Fluxzy Desktop: full control over traffic from the HTTP layer down to transport, deeper visibility into what is happening, and capture in both proxy and proxyless mode.

Download Fluxzy Browse directives

with or without proxy HTTP/2 WebSocket gRPC Offline Open-source core

New to Fluxzy Desktop? Read the overview

What Fluxzy captures, how proxy-less mode works, the full capability matrix, installation, and a guided tour of the interface — the best place to start before diving into a specific feature.

Read the overview

Capture traffic

Capture & Decrypt HTTPS Traffic with Fluxzy

Capture and decrypt HTTPS/TLS traffic with Fluxzy: install and trust the root certificate, route traffic through the system proxy or the transparent full-system tunnel, and inspect decrypted requests and responses.

Capture mobile traffic: Android (Fluxzy Connect) and iOS

Debug HTTPS traffic from Android and iOS apps with Fluxzy. Route Android apps through a local VPN with Fluxzy Connect, no proxy config and no source changes, or point iOS at the proxy, and inspect decoded mobile API calls.

Capture Raw Packets (PCAP / PCAPNG) with Fluxzy

Record raw network packets to PCAPNG with Fluxzy alongside decoded HTTP traffic: enable raw packet capture, turn on NSS key capture for Wireshark decryption, capture, and export a .pcapng file.

Record traffic

Record and save intercepted traffic. Export as HAR and extract raw packets.

Using custom root certificate

Changing root certificate from Fluxzy Desktop settings

Inspect & decode

Inspect HTTP exchange details: headers, body, connection and timings

Open any captured HTTP exchange in Fluxzy to read request and response headers, view a JSON body in the Monaco editor, decode JWT and Authorization headers, inspect the query string, and see connection details (HTTP version, TLS, IP addresses) plus a full timing breakdown.

Inspect and decode gRPC and Protobuf traffic in a debug proxy

Capture, inspect and decode gRPC traffic with Fluxzy. Route a gRPC client through the proxy, read the service and method, and decode the protobuf message either schema-less out of the box or with real field names by pointing Fluxzy at your .proto files, plus read the gRPC status and trailers.

Decode JWT bearer tokens: header, payload and claims

Decode and inspect JSON Web Tokens (JWT) in Fluxzy. When a captured request carries an Authorization: Bearer token, Fluxzy decodes it automatically and shows the algorithm, issuer, subject, audience, expiry, and the full header and payload, with no copy-paste into an online tool.

Inspect OpenAI, Anthropic and Gemini API traffic

Capture and read the exact requests and responses your app sends to OpenAI, Anthropic (Claude) and Google Gemini. Filter to LLM traffic, inspect prompts and completions, follow streaming (SSE) responses, and see tool / function calls.

Search & filter

Search Everywhere: the Ctrl+T command palette for HTTP traffic

Press Ctrl+T (Cmd+T on macOS) to open Search Everywhere in Fluxzy: one box to apply filters, find requests by URL, create rule actions, launch a hooked browser and run commands without hunting through menus.

UI Filters

All ways to isolate exchanges of interest through filters.

Modify & mock

Modify and rewrite HTTP traffic with rules

Create and edit rules in Fluxzy to modify HTTP traffic on the fly: add or update request and response headers, inject authentication, simulate a slow network, forward requests to another server, and scope each change to the right traffic with Apply When filters.

Modify TLS, DNS and HTTP version below the HTTP layer

Fluxzy changes more than headers and bodies. Use rules to impersonate a browser TLS fingerprint, set a JA3 string, spoof DNS, resolve names over DNS-over-HTTPS, force the HTTP version, and present your own certificates. Step by step with screenshots.

Mock HTTP responses without a backend

Return canned HTTP responses with Fluxzy's Mock response rule. Set the status code, content type, headers and body from text or a file to stub an API, simulate errors and run deterministic demos, fully offline.

Importing YAML Rule Files

Import YAML rule configurations to unlock advanced traffic manipulation capabilities in Fluxzy Desktop

Debug & compare

HTTP debugging features

Using breakpoints and live edit to debug your http flows.

Replay and resend HTTP requests to reproduce bugs

Replay any captured HTTP request with Fluxzy, with or without changes, to reproduce bugs and verify fixes fast. Re-run a request in one click, or use live edit to pause and modify it before it is sent.

Comparing exchanges with diff

How to compare two HTTP exchanges side by side using the diff viewer.

Export & integrate

Exporting as cURL

Export intercepted exchanges as cURL command for windows (cmd), bash and postman.

The same engine ships as a scriptable CLI and an open-source .NET library.

Fluxzy CLI Fiddler alternative Charles Proxy alternative