Open-source alternatives to Crow

Starlette is an asynchronous web framework and toolkit for building high-performance web services based on the ASGI specification. It serves as a lightweight foundation for creating web applications with a focus on asynchronous request and response handling. The framework provides specialized toolkits for managing persistent bidirectional WebSocket communication and an asynchronous HTTP server toolkit for routing and middleware. It distinguishes itself by offering a non-blocking background task queue that executes functions after a response has been sent to the client. The project covers a b

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

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

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

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,

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

Starlette is a lightweight ASGI web framework and asynchronous HTTP toolkit used to build high-performance HTTP and WebSocket services. It functions as a WebSocket server framework and a collection of ASGI middleware components for managing network requests through non-blocking asynchronous logic. The framework provides tools for real-time communication via persistent bidirectional channels and infrastructure for high-performance APIs. It includes specialized capabilities for response compression, incremental data streaming, and the execution of non-blocking background tasks after a response

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

aiohttp is an asynchronous networking framework for Python that provides both an HTTP client and an HTTP server. It utilizes the asyncio library to handle network requests and server-side routing through a non-blocking event loop. The framework includes a dedicated toolkit for establishing persistent bidirectional communication channels, enabling the implementation of both WebSocket servers and clients for real-time data exchange. It covers a broad range of asynchronous network programming capabilities, including the development of web servers with customizable routing and the ability to sen

The C++ REST SDK is a library for asynchronous HTTP and RESTful communication in native C++ applications. It provides a non-blocking network client for sending requests and receiving responses, a JSON parser for serializing and deserializing data, and a WebSocket client library for real-time, full-duplex communication. The project includes a dedicated OAuth2 authentication client to manage access tokens and authorization flows for secure communication with protected cloud resources. It utilizes a task-based asynchronous model to coordinate background operations and keep application interfaces

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

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

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

Blade is a lightweight Java MVC web framework built on an embedded Netty server. It packages the entire web application into a single executable JAR that starts the server on launch, following the MVC pattern with fast request routing and minimal configuration. The framework supports plugin-based extensibility, allowing third-party modules to add features like template rendering and static asset serving. The framework distinguishes itself through lambda-style route registration, where routes are defined using lambda expressions that map HTTP methods and URL patterns directly to handler functi

Polka is a minimalist Node.js web framework and HTTP routing engine. It provides a small-footprint server implementation designed for low overhead, mapping URL paths and HTTP methods to specific handler functions. The project utilizes a middleware-based architecture, processing requests through a sequence of functions to handle tasks such as logging, authorization, and data modification. It allows for the organization of these functions into global and path-filtered groups to control execution order. The framework covers core web capabilities including route parameter extraction, request URL

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

Tide is an asynchronous web server framework and HTTP toolkit for the Rust programming language. It provides a system for building high-concurrency network applications and REST APIs using non-blocking I/O and asynchronous runtimes. The framework is centered around a middleware-based request pipeline, allowing developers to intercept and process HTTP requests and responses through pluggable logic layers. It supports a hierarchical route tree to organize endpoints into nested groups that share common path prefixes and scoped middleware. Capability areas include real-time communication via Web

This project is a comprehensive library of reference implementations and patterns for building web applications using the Go Fiber framework. It provides curated templates and implementation guides for creating REST APIs, web servers, and structured backend services. The repository serves as a practical resource for applying architectural patterns, including Clean and Hexagonal architectures, as well as port-and-adapter decoupling. It offers detailed examples for integrating common web features such as OAuth2 authentication, JWT verification, WebSockets for real-time communication, and server

Zend Framework is a comprehensive set of decoupled components for building modular, event-driven web applications. It implements an MVC architecture to separate business logic from the user interface and provides a structured request-handling system through a sequential middleware pipeline. The project features a factory-driven dependency injection container to automate object instantiation and manage class lifecycles. It also includes a comprehensive security suite for verifying user identities and restricting resource access using access control lists and role-based access control adapters.

websockets is a Python library for building WebSocket servers and clients using coroutines and the asyncio framework. It provides a complete toolkit for creating production-ready WebSocket applications, including a coroutine-based framework for handling connections, messages, and lifecycle events, as well as a client library for opening persistent bidirectional connections to remote endpoints. The library manages the full lifecycle of WebSocket connections, including handshake, message exchange, and graceful closure, with support for path-based routing to organize server logic across multiple

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

LoopBack Next is a Node.js API framework used for building REST and multi-protocol APIs. It functions as an OpenAPI server implementation that can either generate machine-readable specifications from code or produce implementation controllers and models from existing specifications. The framework distinguishes itself through a central dependency injection container and a repository-pattern data access layer. This architecture decouples application logic from component construction and persistent storage, allowing for a pluggable system where data sources and business logic are isolated throug

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

Tornado is a Python web framework and asynchronous networking library used to build scalable web applications and high-performance servers. It provides a non-blocking HTTP server capable of handling thousands of simultaneous connections. The project functions as a WebSocket server framework, enabling real-time bidirectional communication and persistent connections between clients and servers. It supports the implementation of custom networking protocols and high-performance networking services beyond standard HTTP. Its capabilities cover asynchronous web application development, concurrent A

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

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.

Feathers is a database-agnostic Node.js application framework designed for building scalable backend systems. It functions as a real-time API framework that provides a server implementation for both REST endpoints and WebSocket connections. The framework decouples application logic from the underlying database technology and communication protocols. This allows a single service to handle both HTTP and Socket requests while separating business logic from the specific data persistence layer. The system organizes data operations through a standardized service-based interface and utilizes hook-b