Socket.IO enables real-time, bidirectional and event-based communication between web clients and servers. It's built on WebSocket protocol with graceful degradation to other techniques like HTTP long-polling. This library provides server-side functionality, allowing you to easily integrate real-time features such as chat applications, data streaming and collaborative tools into your Node.js projects. Simplifies complex real-time communication challenges by providing a simple and familiar API.
Socket.IO's release frequency is highly variable. It had bursts of activity early on (2010-2012), then periods of dormancy. Releases picked up again in 2014-2016, and a major version 3 arrived in late 2020 and version 4 in early 2021. Since then, releases are less frequent and more incremental, tailing off in 2024 and with no releases so far in 2025.
Socket.IO downloads show a generally increasing trend, peaking in July 2025 at 37.2 million. There was a significant jump from March 2024 (23.7 million) to July 2025. August 2025 data is incomplete, showing 18.2 million downloads so far.
