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engine.io

The realtime engine behind Socket.IO. Provides the foundation of a bidirectional connection between client and server

v6.6.11, 24 Sept 2026MITESM + CommonJSTypes: BundledWebSockets and realtime
$ npm install engine.io
npmGitHubHomepage

Key numbers

As of 25 Sept 2026
Weekly downloads
13.4m
+82% over 12 months
Gzip bundle size
-
No Bundlephobia data
Dependencies
9
Direct, from package.json
Last release
today
v6.6.11
GitHub stars
63.2k
10.3k forks
Open issues / PRs
164 / 27
Contributors
-
Commits, last 52 weeks
147

Downloads

Last week 2026-09-15 to 2026-09-21
05m10m15m20mSept 2025Mar 2026Sept 2026High 17.7m (18 Aug 2026)Low 5m (23 Dec 2025)
Weekly npm downloads, one point per week, weeks starting 23 Sept 2025 to 15 Sept 2026. The y axis starts at zero.

13,430,278 downloads last week, 64,697,784 in the last month. The 12-month change of +82% compares the average of the last 4 weeks with the first 4 weeks of the series.

Maintenance

Releases, last 12 months
7156 in total
Latest version
6.6.11, 24 Sept 2026today
First published
3 Jul 2012
Last push to GitHub
24 Sept 2026same day as the snapshot
Repository archived
No
Open issues
164
Open pull requests
27
Commits, last 52 weeks
147
Dependents on npm
258

Major versions

  1. v6 first release 6.0.0, 8 Oct 2021
  2. v5 first release 5.0.0, 10 Mar 2021
  3. v4 first release 4.0.0, 10 Sept 2020
  4. v3 first release 3.0.0, 5 Apr 2017
  5. v2 first release 2.0.0, 22 Jan 2017
  6. v1 first release 1.0.0, 6 Mar 2014
  7. v0 first release 0.1.0, 3 Jul 2012

Recent releases

VersionPublished
6.6.1124 Sept 2026
6.6.103 Sept 2026
6.6.916 Jun 2026
6.6.820 May 2026
6.6.727 Apr 2026
6.6.610 Mar 2026
6.6.522 Dec 2025
6.6.428 Jan 2025
6.6.323 Jan 2025
6.6.29 Oct 2024
6.6.121 Sept 2024
6.6.021 Jun 2024
3.6.218 Jun 2024
6.5.518 Jun 2024

Compatibility

Module format
ESM + CommonJSFrom package.json type, main and exports fields
TypeScript types
Bundled
Node.js engine range
>=10.2.0
Runtimes
-
Unpacked size (npm)
159 kB
Dependencies (9)
wscorsdebugcookieaccepts@types/ws@types/cors@types/nodeengine.io-parser

Install

npm install engine.io

CDN

jsDelivr: 73k requests in 30 days
  • jsDelivrhttps://cdn.jsdelivr.net/npm/engine.io@6.6.11/
  • unpkghttps://unpkg.com/engine.io@6.6.11/
  • esm.shhttps://esm.sh/engine.io@6.6.11

Alternatives

PackageWeekly downloadsGzipLast releaseModuleComparison
sockjs13.9m-4 years agoCommonJS-
Sources: npm registry, npm downloads API, GitHub API, jsDelivr. Data fetched 25 Sept 2026.

Indexability: Indexed.