Open-source alternatives to Tornado

evpp is a C++ network library and framework designed for building high-performance network services using TCP, UDP, and HTTP protocols. It provides an asynchronous event loop to manage nonblocking I/O operations and concurrent network connections across multiple threads. The framework includes specialized tools for asynchronous DNS resolution and a system for asynchronous task scheduling using a managed thread pool. It also features a nonblocking HTTP server and client with integrated connection pooling. The project covers low-level transport layer connectivity for TCP and UDP, as well as hi

Swift NIO is a low-level, event-driven network framework for the Swift language. It serves as an asynchronous network protocol stack and I/O library designed to build high-performance network servers and clients that handle thousands of simultaneous connections. The framework functions as a high-concurrency network engine that dispatches events across multiple CPU cores. It enables the implementation of custom network protocols by processing raw bytes through a sequence of reusable data transformation handlers. The system provides capabilities for non-blocking I/O multiplexing, asynchronous

Sanic is a Python ASGI web framework and asynchronous HTTP server. It is designed to build high-performance web applications and servers that handle concurrent requests using non-blocking logic. The framework implements the Asynchronous Server Gateway Interface standard, allowing applications to be deployed across various ASGI-compatible servers. It utilizes an asyncio-based event loop and integrates a Cython-based runtime wrapper around libuv to manage I/O operations. The system manages traffic through route-based request dispatching and a middleware-based request pipeline. These components

web.py is a minimal Python web framework that provides the core components needed to build web applications: URL routing, template rendering, database access, form handling, and session management. The framework uses a convention-based approach where URL patterns are automatically mapped to handler classes based on their names, eliminating the need for manual route configuration. It exposes applications as WSGI callables, making them deployable with any WSGI-compliant server. The framework distinguishes itself through its metaclass-driven auto-discovery system, which automatically registers h

Robyn is a high-performance asynchronous web framework and server for Python that utilizes a Rust-powered runtime to execute code. It functions as an asynchronous Python web server designed to handle many concurrent requests efficiently through a multithreaded execution model. The project includes specialized capabilities for AI agent request routing, managing communication between agents and external tools. It also serves as a WebSocket communication server, maintaining persistent bidirectional channels for real-time data exchange. The framework covers a broad range of web infrastructure, i

NanoHTTPD is a lightweight, embeddable HTTP server for Java applications. It allows developers to integrate web server capabilities directly into a Java project to handle incoming requests without requiring a standalone installation. The project provides specialized implementations for an HTTPS web server, a WebSocket server for bidirectional real-time communication, and a static file web server. These capabilities enable secure network traffic through SSL certificates and the delivery of local files with automatic MIME type detection. The server includes systems for request routing and hand

Crow is a C++ web framework for building HTTP servers, providing routing, a middleware pipeline, JSON serialization, and WebSocket support. It enables developers to define typed route handlers that extract URL parameters at compile time, return structured JSON responses, and manage real-time bidirectional communication. The framework distinguishes itself with compile-time route pattern parsing and typed argument binding, which eliminate runtime parsing overhead for URL parameters. Its event loop runs on Boost.Asio, and handler execution can be offloaded to a configurable thread pool to keep I

Drogon is a high-performance C++ HTTP web framework and asynchronous web server designed for building web applications and REST APIs. It utilizes an event-driven, non-blocking architecture to handle concurrent HTTP and WebSocket connections, and it implements a model-view-controller structure to separate business logic from presentation. The framework includes an integrated C++ object-relational mapping system and database client for performing asynchronous operations with relational databases and Redis key-value stores. It supports real-time, full-duplex communication via WebSockets and prov

Quart is an asynchronous Python web framework that implements the ASGI specification. It is used to build high-performance HTTP and WebSocket services, JSON REST APIs, and web applications using async and await syntax for non-blocking request handling. The framework supports persistent bidirectional communication via WebSocket API servers and enables the proactive delivery of assets through HTTP server push. It also includes a template engine for rendering dynamic HTML web pages and supports incremental request and response streaming to manage large payloads. General capabilities cover reque

Revel is a full-stack web framework and toolkit for building applications with the Go language. It implements a model-view-controller architecture to separate business logic from user interface rendering, providing a comprehensive system for routing, parameter binding, and session management. The project distinguishes itself with a high-productivity development environment featuring automatic code compilation and hot-reloading, which refreshes the application state and templates upon file changes without requiring manual restarts. It also employs reflection-based parameter binding to automati

LearnPython is a programming tutorial consisting of a collection of practical code examples used to demonstrate Python language features and programming patterns. It serves as a comprehensive learning resource that implements core language concepts through functional code. The project provides specialized guides and samples covering several key domains. These include asynchronous network programming with event loops and coroutines, data visualization using numerical datasets for 2D and 3D plots, and web scraping for fetching content and automating login flows. It also features instructions on

Kemal is a high-performance web framework for the Crystal language, designed for building scalable APIs and web applications. It provides a natively compiled web server environment that leverages ahead-of-time compilation to maximize request speed and minimize memory overhead. The framework is distinguished by a middleware-based routing engine that uses pattern-matching and a chainable pipeline for flexible request filtering. It includes a dedicated server-side template engine for generating dynamic HTML and a WebSocket communication server for bidirectional real-time messaging and state broa

Spark is a lightweight Java web framework and embedded server designed for building web applications with minimal boilerplate. It functions as an HTTP routing engine that maps URL paths and methods to handler functions, providing a specialized domain specific language for web development in Kotlin. The framework enables the implementation of REST APIs and web services through the definition of HTTP routes. It supports the extraction of dynamic path parameters and the transformation of response data into formats such as JSON. Additional capabilities include the ability to serve static files a

Fasthttp is a high-performance networking framework for Go, designed to maximize throughput and minimize memory overhead in demanding web applications. It functions as a specialized HTTP server and client library that prioritizes efficient resource management, allowing developers to build scalable services capable of handling massive concurrent traffic with minimal garbage collection pressure. The library distinguishes itself through a focus on zero-allocation processing and low-level optimization. It achieves this by recycling temporary request and response objects through managed pools and

Trio is an asynchronous I/O runtime and concurrency library for Python. It provides a system for executing non-blocking network and disk operations through a centralized event loop and task scheduler. The library is built on a structured concurrency model, which ensures that asynchronous tasks are bound to a specific lifetime and cannot outlive the scope that started them. It utilizes a nursery-based task manager to track task lifecycles in a parent-child tree, preventing orphaned concurrent operations by requiring child tasks to be joined before their parent scope exits. The framework cover

An asynchronous I/O and reactor event loop library for PHP, this project provides core primitives for coordinating non-blocking operations, managing system resources, and scheduling background tasks. The runtime executes concurrent operations by continuously running tick-based loop iterations that process pending timers, network streams, deferred callbacks, and system signals through efficient system-level polling mechanisms. The library coordinates event-driven execution using asynchronous timers for one-off or periodic tasks, next-tick deferred execution for breaking down workloads, and str

ReactPHP is an asynchronous runtime and event-driven I/O framework for PHP. It provides an environment for executing concurrent tasks through a central event loop implementation and reactor pattern, allowing applications to handle multiple operations without pausing the main execution thread. The project includes a specialized asynchronous socket library for TCP, UDP, and TLS communication, alongside a non-blocking HTTP server and client for streaming web requests and responses. Its capability surface covers asynchronous control flow via promises and fibers, non-blocking network connectivity

Spring PetClinic is a reference application for the Spring Framework, serving as a complete implementation that demonstrates the architecture and best practices for building Java services. It functions as a veterinary practice management system designed to track pet owners, animal records, and clinical visit histories. The project provides a practical example of a containerized web application, illustrating how to integrate a Java application with relational databases like MySQL and PostgreSQL. It serves as a guide for learning how to develop an application using the model-view-controller pat

Undertow is a Java HTTP web server and non-blocking I/O server implementation. It functions as a Jakarta Servlet container and a WebSocket server, providing the infrastructure to execute standardized servlet components and maintain persistent full-duplex communication channels for real-time data exchange. The project is characterized by an asynchronous architecture that utilizes a non-blocking I/O model to handle large numbers of concurrent connections. It incorporates buffer-pooling mechanisms and zero-copy data transfers to reduce memory allocation and garbage collection pressure. The syst

Yii2 is a professional PHP web framework designed for developing high-performance, scalable enterprise web applications. It utilizes a Model-View-Controller architecture to separate data logic, user interfaces, and request handling, ensuring maintainability for large-scale projects. The framework includes a built-in PHP code generator that automates the creation of boilerplate controllers and models by scanning database schemas. It provides an Active Record object-relational mapping system where classes represent tables and instances represent rows to manage data persistence. Additional capa

This is a header-only C++ library that provides implementations for HTTP clients, HTTP servers, and a WebSocket framework. It allows for the creation of network services and the consumption of remote APIs without requiring a separate compilation step or external binary linking. The project features backend-agnostic TLS integration for secure HTTPS and WSS communication and employs a thread-pool model to process concurrent requests. It distinguishes itself with a full-duplex WebSocket state-machine and a middleware-based request pipeline that supports regular-expression path routing. The libr

monoio is a high-performance asynchronous runtime and executor for Rust. It implements a thread-per-core concurrency model that pins tasks to specific CPU cores to eliminate synchronization overhead and data migration. The runtime leverages the io_uring interface to perform non-blocking system calls and reduce kernel-user mode memory copying. It utilizes a high-performance I/O driver and zero-copy TCP stream wrapping to manage data transfer via shared-memory buffers. The project provides capabilities for CPU core affinity management, low-latency system programming, and high-performance netwo

Handy is a C++11 network server framework and event-driven networking engine designed for building high-performance concurrent TCP and UDP servers. It functions as an asynchronous I/O library and an HTTP server implementation that separates asynchronous network I/O from synchronous business logic to simplify server development. The framework distinguishes itself by utilizing platform-specific event notifications to manage millions of simultaneous network connections and providing an SSL/TLS network wrapper for encrypted asynchronous data transmission. It implements a half-sync/half-async proc

uWebSockets is a C++ networking framework that serves as a high-performance WebSocket server library, HTTP web server, and pub-sub messaging system. It provides the infrastructure necessary to handle standard web requests and maintain low-latency, bidirectional connections between clients and servers. The framework is distinguished by its use of template meta-programming for compile-time optimization and zero-copy buffer management to minimize memory latency. It utilizes a backend-agnostic event loop and static route resolution to process network traffic with minimal runtime overhead. The pr

This project is a technical study and analysis guide focused on the internal architecture of Node.js. It provides an in-depth examination of the runtime, focusing on how the engine manages memory handles, executes asynchronous operations, and implements core module logic. The guide specifically analyzes the integration of native C++ classes and functions into JavaScript and documents the behavior of the libuv event loop. It includes detailed references for optimizing performance by identifying V8 compiler bailouts and profiling execution to improve resource efficiency. The material covers a

Nickel is a web framework for the Rust programming language designed to handle HTTP requests and responses. It functions as a server-side toolkit that provides integrated routing, middleware, and JSON deserialization. The framework utilizes a middleware-based request pipeline to insert custom logic and state management into the request-response cycle. It also includes a server-side template engine for generating dynamic HTML pages by merging data with markup templates. The project covers high-level capabilities for REST API development, web application routing, and global error handling to i

GCDWebServer is a lightweight HTTP 1.1 server for iOS, macOS, and tvOS. It serves as an embedded network server for Apple platforms, allowing developers to handle incoming requests through custom synchronous or asynchronous handlers. The project includes a WebDAV server implementation for remote file management, directory browsing, and synchronization using standard network clients. It also provides a web-based file manager that enables users to upload, download, and organize files within an application sandbox via a browser. Additional capabilities include gzip compression, JSON processing,