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Asynchronous Core Libraries

Low-level frameworks providing event loops, futures, and async/await support—enabling non-blocking I/O and high-concurrency applications.

46 projects

51,899 contributors

$119M

Most contributors

Angular

Angular is a TypeScript-based web application framework developed by Google for building dynamic, single-page applications with a structured, component-driven architecture.

Contributors

22,109

Organizations

3,499

Software value

$37M

Tokio

Tokio is an asynchronous runtime for the Rust programming language that enables building reliable network applications. It provides a platform for writing fast, non-blocking network services with features like async I/O, timers, scheduling, and concurrency primitives.

Contributors

3,860

Organizations

1,271

Software value

$3.4M

Tornado Web Server

Tornado is an open-source Python web framework and asynchronous networking library that uses non-blocking network I/O to scale to tens of thousands of open connections. It powers asynchronous web applications and services with its coroutine-based design.

Contributors

2,608

Organizations

791

Software value

$1.4M

Ktor

Ktor is an asynchronous web framework for building connected applications in Kotlin, enabling development of server-side and client-side applications. It provides a flexible, extensible architecture for creating web applications, APIs, and microservices with built-in support for coroutines.

Contributors

2,392

Organizations

598

Software value

$6.3M

Hyperf

🚀 A coroutine framework that focuses on hyperspeed and flexibility. Building microservice or middleware with ease.

Contributors

2,222

Organizations

186

Software value

$10M

ZIO

ZIO is a type-safe, composable library for asynchronous and concurrent programming in Scala. It provides a powerful effect system for building scalable, resilient applications with built-in error handling, resource management, and high performance.

Contributors

2,043

Organizations

379

Software value

$7M

Axum

Ergonomic and modular web framework built with Tokio, Tower, and Hyper

Contributors

1,967

Organizations

625

Software value

$1.2M

Bluebird

Bluebird is a full-featured Promise library for JavaScript that offers superior performance and extra features compared to native Promises. It provides extensive async programming capabilities including coroutines, promisification of callback APIs, cancellation, and detailed error handling.

Contributors

1,716

Organizations

709

Software value

$1.6M

gevent

Coroutine-based concurrency library for Python

Contributors

1,627

Organizations

563

Software value

$13M

Reactor Netty

Reactor Netty is a non-blocking and event-driven network application framework built on top of Netty, providing reactive streams backpressure-ready network engines for HTTP (including WebSockets), TCP, and UDP. It enables building fast and efficient network applications using reactive programming patterns.

Contributors

1,445

Organizations

267

Software value

$3.2M

futures-rs

Futures-rs is a zero-cost asynchronous programming library for Rust that provides core abstractions and utilities for async/await syntax and asynchronous computation. It implements traits and types for working with asynchronous operations in a composable way.

Contributors

1,352

Organizations

523

Software value

$1M

Reactor Core

Reactor Core is a foundational library for building reactive applications on the JVM, providing non-blocking message-passing and backpressure support through reactive streams. It implements the Reactive Streams specification and offers composable asynchronous sequence APIs through its Flux and Mono types.

Contributors

1,331

Organizations

298

Software value

$12M

Mio

Mio is a low-level I/O library for Rust that provides a cross-platform abstraction over operating system event notification mechanisms like epoll, kqueue, and IOCP. It serves as a foundation for asynchronous I/O operations in Rust applications.

Contributors

974

Organizations

374

Software value

$456K

Async

Async is a JavaScript utility library that provides functions for working with asynchronous code, including managing control flow, collections, and concurrency patterns. It helps simplify complex asynchronous operations through functions like series, parallel, waterfall, and queue.

Contributors

949

Organizations

349

Software value

$6.2M

Seastar

High performance server-side application framework

Contributors

831

Organizations

169

Software value

$3.9M

Cats Effect

Cats Effect is a pure functional runtime system for Scala that provides composable asynchronous and concurrent programming capabilities. It implements an IO monad and offers abstractions for managing effects, resource handling, and concurrent computations in a purely functional way.

Contributors

803

Organizations

240

Software value

$1.5M

liburing

liburing is a library that provides a fast and efficient interface for Linux io_uring asynchronous I/O operations. It offers a simplified API for applications to leverage the kernel's io_uring subsystem for high-performance I/O operations, including file operations, network I/O, and other asynchronous tasks.

Contributors

741

Organizations

220

Software value

$2M

Trio

Trio is a Python library for async concurrency and I/O that emphasizes usability and correctness through its structured concurrency model. It provides tools for writing reliable async code including cancellation, timeouts, and resource management.

Contributors

660

Organizations

229

Software value

$1.5M

Wangle

Wangle is a C++ networking library built on top of Facebook's folly library that provides a high-performance asynchronous client/server framework. It implements common client/server protocols and offers abstractions for writing custom network services.

Contributors

658

Organizations

Software value

$1.1M

asgiref

ASGI (Asynchronous Server Gateway Interface) reference implementation and utilities library that provides a standard interface between async-capable Python web servers, frameworks, and applications

Contributors

412

Organizations

174

Software value

$142K

AnyIO

AnyIO is a high-level asynchronous I/O and networking library that provides a unified interface for working with different async backends (asyncio, trio) in Python. It enables writing backend-agnostic async code that can run on any supported event loop implementation.

Contributors

370

Organizations

152

Software value

$748K

Mutiny

Mutiny is a reactive programming library for Java that provides a modern API for asynchronous programming. It offers a declarative approach to handle streams of data and events, with support for backpressure and composable operations.

Contributors

293

Organizations

Software value

$3.1M