Fluxzy

Fluxzy is an HTTP proxy for capturing, examining, debugging, and changing HTTP/1.1, HTTP/2, and WebSocket traffic, including secure connections. Proxyless capture can record app traffic without proxy setup, including apps that ignore system proxy settings. Rules can edit request and response headers, add authentication, simulate slow networks, forward requests, spoof DNS, alter TLS fingerprints, and force HTTP versions. Fluxzy decodes gRPC and Protobuf traffic, with real field names available from .proto files. It can also inspect OpenAI, Anthropic, and Google Gemini API requests and responses, including streams and tool calls. Captures can be exported as HAR, Fiddler SAZ, PCAPNG, cURL commands, .http files, or native .fxzy files. It works offline without an account or cloud sync, and the site says it has no telemetry. The Community edition is free for personal use but adds an x-fluxzy-community header. Pro costs €49.00 once for one developer; Enterprise costs €59.00 once with a three-seat minimum.

Fluxzy offers detailed traffic inspection and editing, including gRPC and selected LLM API traffic. The free Community edition includes all features but has personal-use and header limitations; paid perpetual licenses start at €49.00 once.

Fluxzy is aimed at developers and security engineers who need to inspect or alter network traffic. Its mobile capture options cover Android apps through a local VPN and iOS apps routed to the proxy.

Fluxzy is a traffic inspection and debugging proxy for developers and security engineers. It is best suited to people who need to capture and manipulate traffic from desktop, mobile, or API clients. The perpetual licenses are a practical fit for ongoing work, but the free edition is limited to personal use.

Overview

Fluxzy records and analyzes HTTP/1.1, HTTP/2, and WebSocket traffic over plain or secure channels, with tools to alter requests and responses. Its proxyless capture can record HTTP and HTTPS traffic without proxy configuration, including from apps that ignore system proxy settings. That is useful when a client resists conventional inspection; iOS traffic, in contrast, is routed to the proxy.

The software works offline without an account or cloud sync, and Fluxzy says it has no telemetry. Fluxzy.Core is open source under GPLv3, but Fluxzy Desktop is proprietary, so it is not a fully open-source desktop solution. Desktop downloads publish SHA-256 checksums and CLI downloads SHA-512 checksums; Windows binaries are Authenticode-signed, while macOS builds are Apple-signed and notarized.

Key features

Rules can edit request and response headers, inject authentication, simulate slow networks, forward requests, spoof DNS, change TLS fingerprints, and force HTTP versions. Breakpoints, traffic replay, response mocking, and proxy chaining help engineers reproduce and isolate client behavior rather than merely observe it. WebSocket inspection adds coverage for applications that use persistent connections.

Fluxzy decodes gRPC and Protobuf traffic either without a schema or with real field names supplied from .proto files. It can also inspect OpenAI, Anthropic, and Google Gemini API requests and responses, including streaming output and tool calls. Those capabilities make it a strong fit for debugging API integrations; they are less relevant to teams whose work is limited to ordinary browser requests.

Captures can be exported as HAR, Fiddler SAZ, PCAPNG for Wireshark, cURL commands, .http files, and native .fxzy files, making it easier to move traffic into other debugging workflows. Official NuGet packages provide engine access for .NET Standard 2.1, .NET 6, and .NET 8 applications. Fluxzy Connect captures Android app traffic through a local VPN, while iOS apps can be routed to the proxy.

Pricing

The Community Edition costs nothing and includes all features, but it is restricted to personal use and adds an x-fluxzy-community header. That makes it a useful way for individuals to work with the full toolset, but not a suitable license for professional use; the header also matters when inspecting traffic where request details must remain unmodified.

Pro (Perpetual) costs €49, paid once, billed as “Pay once, own forever.” It covers one developer, removes the personal-use restriction and Community header, and supports Windows, macOS, and Linux. This is the straightforward choice for an individual using Fluxzy at work.

Enterprise (Perpetual) is a one-time payment with a minimum of 3 seats. It costs €59/seat for 1–9 seats, €49/seat for 10–49, and €39/seat for 50+. The minimum seat count makes it a poor fit for a solo buyer, while the lower per-seat rates at larger tiers suit teams. Fluxzy has no free trial, but offers a full refund when contacted within 14 days of purchase.

Platforms

Fluxzy supports Android, iOS, Linux, macOS, and Windows, as well as API and self-hosted use. Mobile capture differs by platform: Android apps can be captured through Fluxzy Connect’s local VPN, while iOS apps are routed to the proxy.

Who it's for

Fluxzy is aimed at developers and security engineers who need to inspect, edit, replay, or mock application traffic. Its proxyless capture is especially valuable for clients that ignore system proxy settings, while gRPC decoding and LLM API inspection suit teams debugging those integrations. People seeking a fully open-source desktop tool, or a free license for work, should look elsewhere.

Pros and cons

• Pro: Proxyless capture can reach applications that ignore proxy settings, avoiding a common obstacle in traffic debugging.
• Pro: gRPC and Protobuf decoding, plus inspection of streaming LLM API traffic and tool calls, cover specialized workflows alongside standard HTTP traffic.
• Pro: Perpetual licenses avoid recurring subscription charges, and the Community edition includes all features for personal use.
• Con: The free edition is barred from professional use and adds an x-fluxzy-community header, so work use requires a paid license.
• Con: Enterprise requires at least 3 seats, which adds cost for small teams that need multi-user licensing.
• Con: Fluxzy Desktop is closed source, despite the GPLv3-licensed Fluxzy.Core.

Alternatives

Web Debugging Proxies is a useful starting point for comparing tools in this category.

• HTTP Toolkit is worth considering for a free basic interception and inspection workflow with manual breakpoints and built-in HTTP client tools; it also supports web.
• Reqable may suit someone who wants a free community tier capped at one device, 100MB of storage, and three rules in each of several categories, or a paid annual option.
• Whistle is a free alternative with Android, iOS, Linux, macOS, web, and Windows support.
• Charles is a paid alternative with a free trial and support for iOS, Linux, macOS, and Windows.
• Fiddler Everywhere is a paid alternative with a free trial and a Lite plan at $10 a month.
• Proxyman offers a free trial, but its trial excludes WebSocket preview, mobile apps, and Network Extension.
• Moni Proxy is another freemium option, with its free plan limiting active mock, rewrite, and breakpoint rules to one each.
• NetworkSpy has a free plan that limits LLM token stream analysis, breakpoints, resource mapping, custom viewer building, and scripting.

Verdict

Fluxzy is a strong choice for developers and security engineers who need broad traffic editing and capture, particularly for proxy-resistant apps, gRPC, or LLM APIs. Its feature-complete personal edition makes evaluation accessible, and its perpetual licenses suit buyers who prefer a one-time purchase. Choose another tool if professional use must be free, if the desktop application must be open source, or if an enterprise seat minimum is impractical.