Open-source alternatives to Starlette

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

Vibora is an asynchronous Python web framework and built-in HTTP server designed for building high-performance web applications. It utilizes an asynchronous event loop and coroutines to process network requests and serve responses without requiring external server wrappers. The project features a high-performance asynchronous schema validator for request integrity, a non-blocking template engine with support for hot-reloading, and a WebSocket communication server for bidirectional real-time data exchange. The framework covers a broad range of capabilities, including modular route management

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

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

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

Litestar is a high-performance Python ASGI web framework designed for building asynchronous APIs and web services. It functions as a type-safe toolkit that leverages Python type hints to provide automatic request validation and response serialization, while natively generating interactive API documentation based on the OpenAPI specification. The framework is distinguished by its integrated dependency injection system, which manages shared resources and resolves complex nested service chains directly within request handlers. It further organizes API development through class-based controllers

RoadRunner is a high-performance application server and process manager designed to serve PHP applications using a persistent worker model. It eliminates bootload overhead and initialization time by keeping application processes alive between requests, acting as a protocol-agnostic proxy that routes traffic to a pool of supervised workers. The server is built with a plugin-based modular architecture, allowing it to be extended with custom Go plugins and compiled into tailored binaries. It distinguishes itself by providing a unified execution model for a wide array of communication protocols,

Iris is a high-performance web framework and API toolkit for the Go programming language. It provides the infrastructure necessary to build HTTP/2 web applications, REST APIs, and MVC-based websites. The project distinguishes itself through a flexible architectural model that supports multiple isolated application instances within a single process and allows for binary-embedded asset loading to eliminate external filesystem dependencies. It features dynamic router hot-reloading and a pluggable view engine for rendering dynamic HTML content. The framework covers a broad range of capabilities,

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

Falcon is a minimalist Python web API framework and high-performance microservices framework. It serves as a resource-oriented API toolkit designed for building RESTful APIs and data plane services that prioritize low overhead, reliability, and scale. The framework implements an ASGI web server interface to handle both synchronous and asynchronous HTTP requests and WebSockets. It features a dedicated HTTP middleware system for intercepting network traffic and executing shared processing logic across multiple API endpoints. Its capability surface covers resource-based routing, HTTP specificat

Uvicorn is an ASGI web application host designed for asynchronous Python web development. It serves applications through a standardized asynchronous server gateway interface to handle non-blocking network traffic and high-concurrency requests. The server manages both HTTP and WebSocket traffic, including the handshaking process required to establish persistent, full-duplex communication channels for real-time data exchange. For development workflows, the project includes a hot-reload mechanism that monitors the filesystem for source code changes and automatically restarts the server process.

This is a full-stack web development framework for Node.js based on the model-view-controller architecture. It provides a comprehensive platform for building applications with an integrated dynamic view engine for HTML markup, a WebSocket communication server for bidirectional real-time messaging, and an embedded NoSQL database for persisting flexible data structures without external dependencies. The framework includes a background task processor that offloads computationally intensive operations to separate worker threads to maintain application responsiveness. It also features an internati

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

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

Oak is a cross-runtime HTTP middleware framework and web server designed to operate across Deno, Node.js, Bun, and Cloudflare Workers. It provides a unified system for building APIs and web servers using a sequential chain of middleware functions and a hierarchical routing engine that maps URL paths to handlers via a nested tree structure. The framework includes a runtime-agnostic serverless adapter that translates diverse cloud provider events into a standard request and response interface. It also features a dedicated WebSocket server implementation for bidirectional real-time communication

Drogon is a high-performance, cross-platform C++ framework designed for building asynchronous web services and server-side applications. It functions as a multi-threaded, event-driven server engine that manages concurrent network traffic and WebSocket connections with minimal latency. By leveraging non-blocking input/output and native code compilation, the framework provides a foundation for scalable applications that operate efficiently across diverse hardware architectures. The framework distinguishes itself through its compile-time template rendering, which transforms dynamic HTML views in

This project is a request router and web framework for the Go programming language. It provides a toolkit for matching incoming HTTP network requests to specific handler functions by evaluating criteria such as URL paths, request methods, headers, and hostnames. The framework distinguishes itself through its flexible matching capabilities, which include support for regular expressions and dynamic variable extraction from URL segments. It allows developers to organize routes into logical hierarchies, share common path prefixes, and maintain a central registry of named routes to facilitate prog

Hono is a lightweight web framework built on Web Standard APIs that executes across JavaScript runtimes including Cloudflare Workers, Deno, Bun, and Node.js.

Echo is a high-performance, lightweight web framework for Go designed for building scalable RESTful APIs and web services. It provides a centralized environment for mapping network requests to handler functions, utilizing a fast radix-tree routing engine to ensure efficient request dispatching. The framework is built around a modular, middleware-centric pipeline that allows developers to execute reusable logic for cross-cutting concerns like authentication, logging, and security across the entire application. What distinguishes Echo is its focus on developer productivity through structured da

uWebSockets is a high-performance networking engine providing an HTTP web server and a WebSocket server framework. It implements a multi-threaded event loop architecture to deploy isolated application instances across multiple CPU cores and includes an SSL/TLS network layer for secure, encrypted communication. The project features a dedicated WebSocket pub/sub engine for distributing messages to specific groups of connected clients. It optimizes network throughput through syscall corking to reduce kernel overhead and employs payload compression to minimize data transfer sizes. The system cov

Oatpp is a high-performance C++ web framework and API development kit used for building REST APIs and web services. It functions as an asynchronous HTTP server that utilizes coroutines to handle thousands of simultaneous connections without blocking threads. The toolkit includes a native C++ object-relational mapping layer for executing SQL queries and transforming database results into data objects. It also provides a WebSocket communication library for establishing full-duplex channels to support real-time data streaming and live media. The framework covers a broad range of capabilities, i

This project is a high-performance PHP framework designed for building scalable services using a resident memory execution model. By maintaining application state in memory across requests, it eliminates bootstrap overhead and provides a persistent environment for long-running processes. The framework distinguishes itself through its integrated support for durable workflow orchestration and asynchronous task management. It enables the execution of complex, long-running business processes that automatically handle failures and state recovery, alongside a background processing system that dispa

Perfect is a server-side Swift framework designed for building high-performance web applications, REST APIs, and backend services. It provides an asynchronous HTTP server that handles web traffic through an event loop, alongside a web template engine for generating dynamic HTML pages. The project includes a WebSocket communication library for implementing bidirectional, real-time data exchange between clients and servers. It also provides a database connector to establish connections and exchange data between Swift applications and external database stores. The framework's capabilities cover

Strawberry is a type-safe GraphQL library for Python that enables the design of schemas using Python type annotations and dataclasses. It functions as an asynchronous GraphQL server and execution engine, providing a bridge to expose schemas across ASGI-compliant web frameworks such as FastAPI, Django, Flask, and Litestar. The project implements GraphQL Federation, allowing for the creation of distributed schemas and entities that merge into a unified supergraph across multiple services. It also includes a dedicated toolkit for the Relay specification, supporting global object identification a

FastAPI is a high-performance Python web framework designed for building REST APIs. It operates as an ASGI web framework, providing a system to create structured HTTP endpoints that automatically serialize data and validate request parameters. The framework utilizes Python type hints to drive data validation and serialization, automatically generating machine-readable OpenAPI and JSON Schema specifications. This process enables the automatic creation of interactive, browser-based API documentation where endpoints can be tested directly. The project includes a dependency injection system for

libhv is a high-performance C/C++ network library and event-driven I/O framework used to build TCP, UDP, SSL, HTTP, WebSocket, and MQTT clients and servers. It provides a non-blocking event loop for managing network sockets, timers, and system signals across multiple threads. The project is distinguished by its integrated support for specialized network roles, including a full HTTP web server with RESTful routing and middleware, an MQTT messaging client for IoT communication, and the ability to implement SOCKS5 and HTTP proxies. It also features a reliable UDP implementation to ensure ordered

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