Open-source alternatives to Whistle

An HTTP proxy library for Go

Mitmproxy is an interactive, programmable network proxy engine designed for traffic analysis and protocol manipulation. It functions as a gateway that intercepts, inspects, and modifies network traffic in real-time, supporting HTTP, HTTPS, WebSocket, DNS, and generic TCP or UDP streams. By acting as a trusted certificate authority, the proxy can dynamically generate and sign certificates to decrypt and analyze secure TLS-encrypted connections. The project distinguishes itself through a highly extensible, event-driven architecture that allows users to automate traffic transformation using cust

gost is a multi-protocol proxy tunnel and secure tunneling server designed to route network traffic through encrypted connections. It functions as a traffic obfuscation gateway and a transparent proxy server capable of intercepting TCP and UDP traffic at the IP level. The project also includes a virtual network interface manager for creating TUN and TAP devices to intercept operating system packets. The system distinguishes itself through a chain-based request routing model, allowing traffic to pass through an ordered sequence of proxy nodes. It provides extensive transport-layer encapsulatio

Reqable is a cross-platform network debugging tool that functions as an HTTP/HTTPS debugging proxy, a REST API client, and a traffic replay tool. It captures, inspects, and modifies live traffic using a local MITM proxy engine, supports VPN tunnel capture for mobile devices, and provides a Python scripting sandbox for custom traffic processing. The application is available on Windows, macOS, Linux, iOS, and Android. The tool distinguishes itself by combining traffic interception with breakpoint-based request modification, allowing users to pause live HTTP traffic for manual inspection and alt

Proxyee is a Java-based network proxy library designed for building custom proxy servers that support traffic interception, inspection, and modification. It functions as a programmable framework for handling HTTP, HTTPS, and WebSocket traffic, providing the necessary tools to analyze and alter request and response data in real time. The project distinguishes itself through its man-in-the-middle capabilities, which include dynamic certificate generation to facilitate the decryption and re-encryption of secure traffic streams. This allows for granular control over network communications, suppor

3proxy is a multi-protocol proxy server and network access control gateway. It functions as a network traffic forwarder capable of routing TCP and UDP traffic across HTTP, SOCKS, and various email and file protocols. The project provides specialized capabilities for secure traffic inspection, including the decryption and analysis of HTTPS and TLS streams through certificate spoofing and mutual authentication. It further supports client identity anonymization by routing outbound traffic through recursive upstream proxy chains. The software covers a broad range of network management functions,

Proxyman is a cross-platform HTTP debugging proxy that captures, inspects, and modifies HTTP, HTTPS, and WebSocket traffic. It functions as a man-in-the-middle proxy, decrypting SSL/TLS traffic to allow real-time inspection and modification of encrypted requests and responses. The tool is designed for debugging web and mobile applications, with capabilities for API mocking and simulation, scriptable traffic modification, and team collaboration on network logs. What distinguishes Proxyman is its deep integration with mobile and cross-platform development workflows. It provides automated certif

Higress is an AI API gateway and cloud-native traffic manager that functions as a Kubernetes ingress controller. It provides a centralized system for routing, securing, and optimizing traffic directed toward large language models, AI agents, and microservice architectures. The project distinguishes itself through deep AI orchestration, including the ability to host and manage Model Context Protocol servers that transform REST APIs into tools for AI agents. It features specialized AI infrastructure for model request proxying, protocol translation across multiple providers, and semantic-based c

Expose is a secure tunneling tool that creates public URLs for local development servers, making them accessible from the internet without complex network configuration. It forwards incoming HTTP requests and responses between a public relay server and a local machine, enabling external services to reach a development environment that would otherwise be isolated behind a firewall or VPN. The project distinguishes itself through a comprehensive set of webhook debugging and inspection capabilities. It captures all incoming webhook requests and displays them in a real-time dashboard or command-l

Expose is a PHP-based tunneling service and local environment proxy that exposes local servers to the internet via public URLs. It provides a secure way to share development previews and test APIs without deploying to a remote server. The project is distinguished by its support for self-hosted tunneling infrastructure, allowing users to deploy a private server for full control over data and network configuration. It includes a dedicated HTTP webhook debugger for capturing, inspecting, and replaying incoming requests to verify system behavior in a local environment. The toolset covers network

This project is a cloud storage link resolver and direct link generator that transforms sharing links from various cloud and music sharing platforms into direct download URLs. It functions as a programmatic interface that returns file metadata and download paths in JSON format for use in external applications and download managers. The system features a JavaScript parser framework that allows for the implementation of new link conversion logic via dynamic scripts without requiring application recompilation. To maintain service availability, it includes a request router that distributes outgoi

Stoatchat is a real-time chat server and messaging backend that utilizes WebSockets to handle instant communication, live event updates, and user presence tracking. The project incorporates an encrypted file storage system and cloud storage layer that applies AES encryption to binary data before upload. It also functions as an HTTP content proxy server to mask user IP addresses when fetching media from third-party services and as a push notification gateway to ensure reliable alert delivery via a background dispatch queue. The system includes role-based access control to manage user permissi

Wfuzz is a web application fuzzing framework that automates the injection of payloads into HTTP requests to discover hidden resources, parameters, and vulnerabilities. It functions as a content discovery scanner, a brute-force tool for credential guessing, and a plugin-based vulnerability scanner, all within a single modular system. The tool distinguishes itself through its plugin-based extensibility, allowing custom Python modules to add new payload sources, output printers, or scanning logic without modifying core code. It supports concurrent request dispatch using thread-based parallelism

BrowserSync is a web development synchronization tool and live reload server. It functions as a local static web server, a reverse proxy server for existing sites, and a browser testing orchestrator that coordinates page state across different browsers and physical devices. The tool is distinguished by its ability to mirror user interactions, such as clicks, scrolls, and form inputs, in real time across all connected devices. It also provides a web-based device control interface and the capability to create public URL tunnels for remote testing of local sites. The system covers a broad range

Turndown is a JavaScript library designed to transform HTML documents into structured Markdown. It functions as a flexible engine that parses web content by traversing the document object model and applying rule-based transformations to convert elements into their corresponding text-based syntax. The tool distinguishes itself through a modular architecture that allows for extensive customization of the conversion process. Users can define custom conversion rules to handle specific elements, implement content filtering to discard unwanted nodes, and configure character escaping to ensure outpu

Reactotron is a desktop-based development environment designed for inspecting, monitoring, and manipulating mobile and web applications in real time. It functions as a centralized hub that connects to a running application via a persistent WebSocket connection, allowing developers to observe internal state, network traffic, and console output without manual instrumentation. The tool distinguishes itself through a modular plugin architecture that enables custom debugging commands and specialized extensions. It provides advanced diagnostic capabilities, including the ability to overlay design m

Foreman is a lifecycle infrastructure management platform used for automating the provisioning, configuration, and monitoring of physical, virtual, and cloud servers. It serves as a central hub for managing the entire lifespan of a server, from initial deployment and operating system upgrades to decommissioning and auditing. The platform functions as a hybrid cloud manager and bare-metal provisioning tool, providing a unified interface to control virtual machine lifecycles across diverse hypervisors and public cloud providers. It automates hardware discovery and operating system deployment us

proxyee-down is an HTTP proxy download manager and multi-threaded download client. It is designed to route file download requests through an HTTP proxy server to accelerate data retrieval and bypass network restrictions. The tool increases transfer speeds by splitting large files into smaller chunks and downloading them concurrently across multiple TCP connections. It features the ability to update expired or changed source URLs for existing tasks, allowing interrupted downloads to recover and resume without losing previously downloaded segments. The system provides controls for manual downl

This project is a Go-based HTTP proxy server designed as a censorship circumvention tool. It functions as an upstream proxy manager and SOCKS5 tunneling gateway that routes network traffic between clients and destination servers to bypass network restrictions. The system differentiates itself through automated proxy routing, which detects unreachable websites and automatically switches traffic between direct access and a pool of parent proxies. It includes a PAC file generator to produce proxy auto-config files for browsers and integrates SSH tunneling to establish secure remote sockets. Bro

Tinyproxy is a lightweight HTTP and HTTPS proxy daemon designed for POSIX operating systems. It functions as a system-level network proxy that manages web traffic with minimal resource overhead. The project supports multiple routing modes, including reverse proxying to forward requests to backend servers and transparent proxying to intercept network traffic without client-side configuration. It also includes a header filter to modify or block specific HTTP headers for privacy and security. The software incorporates network access control based on client subnets and protocol filtering. For sy

spy-debugger is an HTTP proxy debugging tool designed for intercepting and analyzing network traffic from mobile devices, WebViews, and mobile browsers. It functions as a network packet capture tool and a remote browser inspector, allowing users to monitor HTTP and HTTPS requests wirelessly without the need for USB cables. The project distinguishes itself by using script injection to enable remote debugging. It injects JavaScript into HTTP response bodies, providing the ability to inspect HTML and CSS elements and perform live page content editing directly on the mobile screen. Additionally,

Dev-sidecar is a local HTTP proxy tool designed to optimize development environments by intercepting and modifying network traffic. It functions as a man-in-the-middle service that routes outgoing requests through custom endpoints, enabling developers to accelerate access to remote services, manage package registry connections, and bypass regional connectivity restrictions. The tool distinguishes itself through its ability to perform dynamic DNS resolution overrides and certificate-based traffic inspection, allowing for granular control over network paths and secure data analysis. It employs

UnblockNeteaseMusic is a network gateway and proxy server designed to restore playback for unavailable songs on Netease Cloud Music. It functions as an HTTP traffic proxy that intercepts requests to unlock restricted digital content and bypass regional availability limits. The project acts as a regional content gateway, using custom IP parameters and request rerouting to bypass geographic blocks. It restores access to restricted tracks by diverting network traffic from official servers to alternative music sources. The server manages network traffic routing through domain-based routing and U

Raycast Extensions is an open-source platform for building and distributing self-contained plugins that integrate with the Raycast desktop application. It provides an extension plugin framework where developers create packages using TypeScript, React, and Node.js, with each extension declaring its commands and permissions through a static manifest. The platform includes a hot-reload development server that watches source files and triggers live UI updates without restarting the host application. The platform distinguishes itself through deep AI integration capabilities, allowing extensions to

httptap is a network utility for intercepting system-level packets and monitoring the HTTP and HTTPS traffic of Linux processes. It functions as a network packet sniffer and traffic monitor designed to capture and display real-time requests and responses sent by local applications. The project includes a local traffic redirector that maps remote hostnames or IP addresses to localhost for service testing. To support detailed inspection, it features a TLS termination proxy for decrypting HTTPS traffic and a HAR file exporter that dumps captured data into the standard HTTP Archive format for ext

Pingora is a Rust-based framework for building high-performance network services, including HTTP reverse proxies, layer seven load balancers, and TLS termination proxies. It serves as an asynchronous network library designed to intercept and route HTTP, gRPC, and WebSocket traffic between clients and upstream backend servers. The project enables zero-downtime service updates by handing over listening sockets between processes during binary or configuration upgrades. It utilizes a programmable multi-phase pipeline to modify request and response bodies and headers, and it provides a pluggable T