Companies Using Socket.io

On our data, mostly sites running a chat, engagement or marketing widget that bundles it, plus hosted platforms and developers' own apps. On 6 November 2026, Cardinal Health, TAP Air Portugal, Hero MotoCorp, Saab, Halkbank and HDFC Life all loaded it. In a random 40-domain sample, 16 of the 24 live sites got it from a vendor or a platform.

We count 29,026 domains loading Socket.io in our November 2026 crawl, after removing 17,719 from a raw 46,745, mostly for-sale and gambling pages. They're domains, not customers: Socket.io is free, MIT-licensed software, and many of these sites carry it inside another vendor's widget. 12,509 match a company.

Socket.io holds 0.03% of JavaScript Libraries at TechnologyChecker.io, 82nd, on 29,026 domains. Raphael is 81st and Snap.svg 83rd. jQuery leads with 18.44%, then core-js (12.13%) and jQuery Migrate (9.85%). Those load on ordinary pages; Socket.io appears only where a site, or a widget on it, needs live messaging.

Our JavaScript Libraries table is led by jQuery (16,457,738 domains), core-js (10,827,094), jQuery Migrate (8,786,948) and jQuery UI (5,108,595), but none of them does Socket.io's job. For real-time messaging, the usual alternatives are the browser's built-in WebSocket API, which needs no library, or a hosted real-time service with its own SDK.

The United States, with 2,908 of the 12,509 companies we matched, then Germany (1,614), Brazil (879), India (793), France (544) and the United Kingdom (481). India's entries include shops on the Mystore platform, such as Amul's and Hero MotoCorp's, which load Socket.io in the platform's shared code.

Mostly small ones. 56.39% of matched companies with a known size have 1 to 10 employees and 24.49% have 11 to 50. 268 have more than 1,000 staff. At those, Socket.io usually comes with a vendor's widget, as on Cardinal Health's careers site or TAP Air Portugal's home page, rather than from the company's own developers.

Mostly founded since 2000. 43.14% of matched companies with a founding year started in the 2010s, 17.83% in the 2020s and 17.68% in the 2000s. 21.35% predate 2000, among them banks such as Halkbank and TEB that run Socket.io in their own site code, and older firms that got it through a chat widget.

On our data: a retail, software or IT services company with 1 to 10 staff, founded in the 2010s, in the US, Germany, Brazil or India, on a Bootstrap site served by Nginx, with a chat or engagement widget that loads Socket.io for it. A second profile is a developer's own real-time app: a portal, dashboard or browser game.

Two-way, low-latency messaging between a browser and a server: live chat, notifications, live scores and multiplayer games all appear in our sample. Its site says it connects over WebSocket when it can and falls back to HTTP long-polling. On our data, chat is the commonest single use: 4 of 24 live sites in a 40-domain sample loaded it inside a chat widget.

WebSocket is the browser's protocol; Socket.io is a library that uses it. Socket.io's documentation says it connects over WebSocket where possible, falls back to HTTP long-polling and reconnects automatically. It also adds metadata to each packet, so a Socket.io client can't connect to a plain WebSocket server, and a plain WebSocket client can't connect to a Socket.io server.

Yes. Socket.io is open source under the MIT licence, per its GitHub repository, and the client is served free from cdn.socket.io, cdnjs and jsDelivr. Its documentation lists 4.8.4, from September 2026, as the latest client release. Older clients persist: two sites in our 6 November 2026 sample reported 0.9.x versions.

No. It's a library: a browser client plus a server package for Node.js, with other server implementations in languages such as Java, which you add to an existing app. The client registers a global io object, one of the signals we detect. We file it under JavaScript Libraries, where it ranks 82nd.

Look in the page's scripts or network requests for socket.io.js or socket.io.min.js, or for requests to a /socket.io/ path with EIO= in the query string. In the browser console, typeof io.Socket returns "function" when the client is loaded. Then check which script loaded it: on our data it's often a chat widget, not the site's own code.