Whistle

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What Whistle is

Whistle is an open-source network debugging proxy for capturing, inspecting and changing traffic. It supports HTTP, HTTPS, SOCKS and reverse proxying, while configurable rules can modify requests and responses. The Network interface filters captured requests in real time, and Composer supports replay and editing. WebSocket and TCP traffic can be inspected; users can pause or ignore transmission and send custom data. HTTPS decryption requires enabling HTTPS capture and installing Whistle’s root certificate. The desktop edition has a graphical interface for macOS, Windows and Linux. Its command-line version is intended for headless Linux servers, Docker containers, embedded systems and IoT devices. Mobile capture instructions cover iOS and Android devices configured to use the proxy and trust its root certificate. Plugins extend its functions, and Whistle can also be included in a project as an NPM module. The integrated Weinre tool supports debugging webpages on mobile devices from a computer on the same network. Internal request authentication can use a username and password; controlling proxy request permissions requires a plugin or custom plugin development. The project is MIT-licensed.

Who it suits

Whistle suits developers debugging network requests across desktop, mobile and headless environments. It may also suit project teams seeking proxy functionality through plugins or an NPM dependency.

What it does well

Supports HTTP, HTTPS, SOCKS and reverse proxying.
Can replay and edit captured requests.
Inspects WebSocket and TCP data.
Offers graphical desktop and command-line editions.
MIT-licensed and extensible through plugins.

What to know first

HTTPS decryption requires installing its root certificate.
Mobile capture requires proxy setup and certificate trust.
Proxy request permission controls require a plugin.

Limits

HTTPS decryption requires enabling HTTPS capture and installing the root certificate. Proxy request permission control requires a plugin or custom plugin development.

Getting started

Open https://wproxy.org/en/.
Choose the desktop version for macOS, Windows, or Linux, or the command-line version for a supported server environment.
Configure a device to use Whistle as its proxy for mobile packet capture.
Enable HTTPS capture and install Whistle’s root certificate if HTTPS decryption is needed.
Use the Network interface to filter requests, then edit or replay them with Composer.

Verdict

Whistle combines traffic capture and editing with desktop, command-line and mobile debugging workflows. Plan for certificate setup for HTTPS and mobile capture, and use a plugin if proxy request permission control is needed.

Questions

Does Whistle cost anything?

Whistle is free and open source. Its project README identifies the license as MIT.

Which platforms are supported?

The listed platforms are Android, iOS, Linux, macOS, web, and Windows. The desktop application has a graphical interface for macOS, Windows, and Linux.

Can Whistle capture HTTPS traffic?

Yes. HTTPS decryption requires enabling HTTPS capture and installing Whistle’s root certificate.

Can Whistle edit or replay requests?

Yes. Rules can modify requests and responses, and Composer supports editing and replaying requests.

Can it be extended or integrated into a project?

Whistle supports plugins and can be used as an NPM module dependency.

Who makes Whistle?

The official site footer credits Aven Wu.

Facts from Whistle's own pages

Access control: The FAQ documents optional username and password authentication for Whistle's internal requests and says proxy request permission control requires a plugin or custom plugin development. · wproxy.org, 4 Oct 2026
Access controls: The FAQ describes internal request authentication using username and password startup options; proxy request permission control requires a plugin or custom plugin. · wproxy.org, 5 Oct 2026
Built in tools: The product page names Weinre among its built-in debugging tools. · wproxy.org, 5 Oct 2026
Capture tools: The Network interface supports real-time filtering of captured requests and offers request replay and editing through Composer. · wproxy.org, 4 Oct 2026
Desktop platforms: The installation page lists macOS, Windows, and Linux desktop systems with a graphical interface. · wproxy.org, 5 Oct 2026
Extensibility: Whistle functions can be extended through plugins, and Whistle can also be used as an NPM module dependency. · wproxy.org, 4 Oct 2026
HTTPS capture: HTTPS traffic decryption requires installation of the Whistle root certificate. · wproxy.org, 5 Oct 2026
Intended use: The installation page describes command line use on headless servers and desktop use on macOS, Windows, and Linux. · wproxy.org, 5 Oct 2026
License: The project README identifies the license as MIT. · github.com, 5 Oct 2026
Maker attribution: The official site footer credits Aven Wu and shows copyright beginning in 2015; it does not state a headquarters location. · wproxy.org, 4 Oct 2026
Mobile devices: Whistle's mobile packet capture instructions cover iOS and Android devices configured to use the proxy and trust its root certificate. · wproxy.org, 4 Oct 2026
Plugin hooks: Plugins can generate and issue HTTPS certificates, authenticate proxy requests, access request and response metadata, set rules dynamically, and handle forwarded requests. · wproxy.org, 4 Oct 2026
Plugin support: Whistle functions can be extended through plugins, and the plugin screen supports installation, configuration, updates, and uninstallation. · wproxy.org, 5 Oct 2026
Product: Whistle is a cross-platform network debugging proxy. · wproxy.org, 5 Oct 2026
Project integration: Whistle can be integrated into a project as an NPM module. · wproxy.org, 5 Oct 2026
Proxy protocols: It supports HTTP, HTTPS, SOCKS and reverse proxying, and can intercept and modify network traffic. · wproxy.org, 4 Oct 2026
Remote debugging: The integrated Weinre tool lets developers debug webpages on mobile devices from a computer on the same network. · wproxy.org, 4 Oct 2026
Rule based editing: Users configure rules to modify requests and responses. · wproxy.org, 5 Oct 2026
Security documentation: The FAQ says internal request authentication can prevent unauthorized access to rules and configurations. · wproxy.org, 5 Oct 2026
Server environments: The command line version is intended for Linux servers without a graphical interface, Docker containers, embedded systems and IoT devices. · wproxy.org, 4 Oct 2026
Server use: The command line version is listed for headless Linux servers, Docker containers, embedded systems, and IoT devices. · wproxy.org, 5 Oct 2026
Traffic support: It supports HTTP, HTTPS, SOCKS, and reverse proxy modes and can intercept and modify network traffic. · wproxy.org, 5 Oct 2026
WebSocket and TCP: Users can inspect WebSocket or TCP request and response data, pause or ignore transmission, and send custom data through Composer. · wproxy.org, 4 Oct 2026

Where Whistle stands on Freedom251

Web Debugging Proxies#27 of 27