# SockJS

WebSocket emulation - Node.js server

Repository: https://github.com/sockjs/sockjs-node
Canonical: https://ross.abutalabs.com/products/sockjs
Homepage: http://sockjs.org
Language: JavaScript
License: MIT
License Family: permissive
Topics: sockjs, javascript, nodejs, node, websocket, real-time
Last push: 2026-07-21T01:47:23+00:00

## Health v2 (maintenance only)
Score: 65/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 93, release rhythm 8, longevity 100
- inputs: {"age_days": 5521, "days_push": 44, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2101, forks 306 (observed 2026-08-28T04:06:13.644180+00:00)

## What it is
SockJS-client is a browser JavaScript library that provides a WebSocket-like object for low-latency, full-duplex, cross-domain communication between browser and server. It uses native WebSockets when available and falls back to various browser-specific transport protocols for environments where WebSockets are unsupported, such as behind restrictive corporate proxies.

## Use cases
- add real-time messaging to a web app behind a corporate proxy that blocks WebSockets
- build a chat application that works in all modern and legacy browsers
- establish full-duplex cross-domain communication between browser and Node.js server
- provide WebSocket-like API with automatic transport fallbacks
- stream live updates to browsers that don't support the WebSocket protocol

## When to choose
- you need WebSocket-like real-time communication but must support old browsers or restrictive proxies
- you want a mature, cross-browser fallback layer with a Node.js server counterpart
- your deployment environment may not support native WebSockets

## When to avoid
- all your target browsers and networks support native WebSockets
- you need a non-Node.js server implementation without a SockJS counterpart
- you want modern alternatives like native WebSocket APIs or Socket.IO's ecosystem

## Facets
- artifact type: library
- maturity: maintenance
- function: websocket, http-client, middleware
- domain: web-development, networking
- platform: browser, cross-platform
- tags: websocket-emulation, fallback-transports, browser-library, real-time-communication, real-time, nodejs

## Member repositories
- sockjs/sockjs-node (main) score 65
- sockjs/sockjs-client (sdk) score 66

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:06:13.644180+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:26:41.816640+00:00, confidence not recorded.
  - readme: https://github.com/sockjs/sockjs-node (fetched 2026-08-28T04:06:13.644180+00:00, sha e09317c0827d)
  - registry_npm: https://registry.npmjs.org/sockjs-client (fetched 2026-08-29T08:27:20.436730+00:00, sha 4d2ac771eee2)
- Data as of 2026-08-30T08:39:29.467469+00:00.