Open-source alternatives to Primus

This is a non-blocking network client for Java applications that provides asynchronous HTTP request capabilities and bidirectional WebSocket connectivity. It leverages a Netty-based architecture to handle high volumes of network input and output. The library utilizes native transport abstractions such as Epoll, KQueue, and io_uring to reduce system latency. It supports HTTP/2 multiplexing to run multiple concurrent request-response streams over a single connection and provides automatic response body decompression for various formats. Core capabilities cover the management of complex network

Wretch is a chainable HTTP client library and Fetch API wrapper designed to simplify network request configuration, response parsing, and error handling. It functions as a network request manager and middleware framework for managing the end-to-end lifecycle of HTTP calls. The project is distinguished by a fluent interface for request configuration and a modular extension system. It utilizes a programmable response resolver to automate parsing and a plugin-based architecture to add new capabilities to request and response objects. The library covers a broad range of operational capabilities,

This is a Golang client library for interacting with a cloud native distributed messaging system. It provides the necessary tools for Go applications to exchange messages using publish-subscribe and request-reply patterns, as well as specialized clients for managing persistent streams and distributed storage. The library includes a JetStream client for durable message streaming and replay, a Key-Value store client for managing distributed state with versioning and watchers, and an Object Store client for the storage and retrieval of large binary files via chunked delivery. The implementation

Socket.io is a real-time communication engine that enables bidirectional, event-based data exchange between clients and servers. It provides a robust transport-agnostic protocol layer that automatically manages connection lifecycles, including heartbeat signals, automatic reconnection, and seamless fallback between WebSockets and HTTP long-polling. By maintaining persistent links, it ensures reliable messaging across diverse network environments. The project distinguishes itself through a scalable, distributed architecture that supports multi-node synchronization and room-based message routin

openapi-ts is a tool and orchestrator used to convert OpenAPI specifications into type-safe TypeScript SDKs and HTTP client implementations. It automatically generates typed interfaces and request functions from API definitions to ensure consistency between the server and the client. The project employs a transport-agnostic client interface, decoupling high-level API calls from the underlying network library. It uses a plugin-based generation pipeline and a custom plugin architecture to allow for the customization of output types and validation schemas. The system provides capabilities for n

Rueidis is a high-performance Redis client library for Go that provides a type-safe and asynchronous interface for interacting with Redis servers. It includes a full implementation of the Redis serialization protocol and a dedicated connection manager to handle pooling, multiplexing, and automatic pipelining. The library is distinguished by its support for RDMA connectivity to reduce latency and CPU overhead. It features a distributed lock manager that implements majority-based locking and optimistic concurrency control, as well as client-side caching with invalidation signals to minimize net

MobileIMSDK is an open-source instant messaging framework that provides reliable real-time message delivery across iOS, Android, Java, HarmonyOS, and web platforms. At its core, it offers a unified communication layer that transparently supports UDP, TCP, and WebSocket transports, enabling developers to send and receive messages without managing protocol differences or connection state. The framework includes an automatic reconnection engine that detects network outages and restores connections without manual intervention, with built-in message retransmission and deduplication to guarantee exa

Flask-SocketIO is a Flask extension that integrates the Socket.IO real-time communication protocol into Flask applications, enabling persistent bidirectional connections between servers and clients. It transparently switches between WebSocket and HTTP long-polling while maintaining a persistent session identity, and provides a full event-driven framework for real-time web application communication. The library distinguishes itself with support for namespace multiplexing, allowing event handlers to be isolated into separate namespaces with independent lifecycle and routing. It also offers room

netty-socketio is a Java implementation of a Socket.IO server designed for real-time bidirectional communication between clients and servers. It functions as a real-time event engine and WebSocket communication server, utilizing the Netty network framework to manage high-performance socket connections. The project enables distributed socket server scaling by acting as a distributed message broker. It synchronizes client states and broadcasts messages across multiple server nodes through the use of an external data store. The system manages traffic via namespace-based connection routing and r

Socket.IO Client is a real-time WebSocket client library that establishes persistent bidirectional connections to a server, with automatic fallback to HTTP long-polling when WebSocket connections are unavailable. It provides an event-based bidirectional messaging framework where clients and servers exchange named events with serializable data, supporting acknowledgements and timeouts for reliable communication. The client distinguishes itself through automatic reconnection with exponential backoff, maintaining connection reliability by monitoring health and reconnecting with increasing delays

Got is a promise-based HTTP request library for Node.js that supports HTTP/2 and streaming. It provides a system for making network requests with a focus on asynchronous control flow and type-safe API client development. The library is distinguished by its middleware-based request lifecycle, which uses interceptors and plugins to modify request options and response data. It includes a configurable automatic retry mechanism with backoff strategies, a built-in HTTP response cache, and a cookie-jar system for maintaining persistent sessions. Broad capabilities cover data handling through duplex

The inspector is a diagnostic and validation tool for the Model Context Protocol. It provides an interactive interface and a transport proxy to discover, inspect, and execute the tools, prompts, and resources provided by an MCP server. The project serves as a debugger and compliance tester to verify that server implementations adhere to the protocol specification and JSON-RPC standards. It allows for real-time monitoring of message exchanges and logs between clients and servers across various transport layers, such as standard input/output and Server-Sent Events. The tool covers a broad rang

SignalR is a .NET real-time web framework designed to push content from a server to connected browser and non-browser clients. It provides a server-to-client push framework and a remote procedure call system that enables bidirectional communication over persistent connections. The library utilizes WebSockets to establish full-duplex connections and includes a transport-layer abstraction to manage different network protocols. It employs client-side connection negotiation to determine the best available communication protocol during the initial handshake. The system manages persistent connecti

Sails is an enterprise Node.js web framework designed for building scalable applications using a model-view-controller architecture. It functions as a realtime web application framework and a database agnostic object-relational mapper, providing a structured environment for developing server-side applications. The framework enables bi-directional data exchange between clients and servers via persistent connections to support real-time features. It utilizes a consistent interface to interact with various relational and non-relational data stores, allowing the application to remain independent

Yoga is a GraphQL server framework and runtime-agnostic HTTP handler used to build and deploy GraphQL APIs. It functions as a toolkit for managing schemas and resolvers, providing a spec-compliant environment for hosting APIs across diverse JavaScript runtimes, including Node.js, Deno, Bun, and serverless cloud environments. The project distinguishes itself through its ability to act as an Apollo Federation gateway, composing multiple subgraphs into a single unified supergraph. It also serves as a dedicated subscription server, delivering real-time data streaming via both WebSockets and Serve

PartyKit is a serverless WebSocket backend platform for building real-time multiplayer applications. It provides a globally distributed edge computing runtime that runs stateful server code close to users, with automatic scaling and hibernation for idle rooms. The platform handles WebSocket connections, HTTP requests, and durable storage without requiring infrastructure management, and includes a client and server SDK with hooks, storage, and Yjs integration for building collaborative features. The platform distinguishes itself through per-room isolation using Durable Objects, where each uniq

webpack-dev-server is a local web server designed to serve webpack bundles and trigger browser refreshes when source files change. It functions as a development environment that hosts bundled applications and provides a live reloading workflow. The project distinguishes itself by supporting hot module replacement to update modules in a running application without a full page reload. It also acts as an HTTP proxy to redirect network request paths to different backends and provides history API fallbacks specifically for hosting single-page applications. The server includes capabilities for mon

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

This is a minimal WebSocket library for Go designed for bidirectional real-time communication. It serves as a network protocol implementation for managing handshakes, frame masking, and control signals to enable the exchange of text and binary messages over persistent connections. The library distinguishes itself by providing a connectivity layer that wraps browser WebSocket APIs for applications compiled to WebAssembly. It also functions as data compression middleware, utilizing deflate compression to reduce bandwidth usage for transmitted messages. The project covers a broad range of netwo

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

Memberlist is a Go library used for maintaining distributed cluster membership and failure detection via a peer-to-peer gossip protocol. It functions as a cluster state synchronizer, allowing nodes to track active members and propagate metadata without a central coordinator. The library implements a secure gossip mechanism using AES-GCM encryption to protect inter-node communication and membership data. It distinguishes its failure detection through a suspicion-based model and adaptive timeout scaling, which reduces false positives caused by transient network latency. The project provides ca

Chisel is a network tunneling tool that facilitates secure communication by encapsulating TCP and UDP traffic within HTTP requests. It functions as a connection multiplexer, consolidating multiple logical network streams into a single persistent connection to improve throughput and reduce overhead. By leveraging standard web protocols, the system enables firewall traversal and provides a mechanism for remote port forwarding and proxying. The project distinguishes itself through its focus on resilient connectivity and granular access control. It maintains persistent network sessions across uns

Hyper is a low-level networking library designed for building high-performance HTTP clients and servers. It provides a foundational toolkit for creating network services that leverage asynchronous execution and memory-safe data handling, supporting both HTTP/1 and HTTP/2 protocols. The library distinguishes itself through a protocol-agnostic architecture that separates transport logic from HTTP semantics. It utilizes a service-trait abstraction to decouple network logic from the underlying transport, enabling developers to inject custom middleware for request interception and response transfo

Crawlee is a web scraping framework designed for building scalable, reliable, and distributed data extraction pipelines. It provides a unified interface for managing headless browser automation and lightweight HTTP requests, allowing developers to handle complex web navigation, dynamic content rendering, and large-scale data collection within a single, modular architecture. The project distinguishes itself through its resource-aware concurrency controller, which dynamically scales task execution based on real-time CPU and memory usage to prevent host machine exhaustion. It also features a rob

This project is a command-line development web server designed to serve static files and proxy network requests. It functions as a modular, middleware-based server that allows developers to chain custom functions to handle request parsing, response compression, and URL rewriting. The server distinguishes itself through its ability to simulate complex network environments and production-like security configurations. It supports secure encrypted connections via HTTPS and restricts access to hosted resources using basic authentication protocols. Additionally, it provides specialized routing for

pgdog is a PostgreSQL sharding proxy, distributed SQL router, and connection pooler. It is designed to enable horizontal data distribution by splitting tables and indices across multiple independent servers to scale storage and processing capacity. The project distinguishes itself through online resharding capabilities, using logical replication to move data between shards without application downtime. It supports multiple routing strategies, including hash, list, and range-based query routing, and manages distributed atomic transactions using a two-phase commit process to ensure consistency

Mars is a cross-platform networking SDK and high-performance logging framework. It provides a network reliability layer for managing short and long-lived connections across different operating systems, alongside a diagnostic tool for recording system events to disk with minimal application overhead. The project features a persistent connection manager that maintains bidirectional server links using heartbeats and sequence tracking. It includes a traffic control engine to prevent server request avalanches by limiting the frequency and volume of outgoing requests. To improve connectivity, it ut