Download websites that use HeadJS

About HeadJS

Nothing about HeadJS is growing, and the absence of growth is what makes its remaining population interesting. HeadJS is a JavaScript libraries from the period when getting scripts onto a page in the right order was a genuine engineering problem. Released in 2011 under a MIT license and written in JavaScript, HeadJS let a developer request several files in parallel while still controlling the order in which they executed, and added feature detection so a page could decide at runtime whether it needed a fallback.

Browsers then absorbed most of that work. Native async and defer attributes, followed by module bundlers and native modules, removed the reason to carry a separate loader at all. New projects stopped reaching for HeadJS, but working code is rarely deleted from a live page, so the library survived by inertia rather than by choice. As of October 2026 we detect HeadJS on 959 sites. The figure is better read as a census of front ends that have not been rebuilt in a long time than as a measure of adoption.

A page still carrying the loader is therefore describing its own maintenance schedule. Sites in this population tend to run other tooling of the same vintage, to have been built under an agency relationship that has since ended, and to sit outside any modern build pipeline. For anyone selling redesigns, migrations or managed maintenance, the useful property is not the loader itself but the age of the codebase around it. For a dependency or security researcher, an abandoned loader is a reasonable place to start looking for other abandoned dependencies on the same host.

Detection has a floor worth stating plainly. We recognise HeadJS when it is served as an identifiable file or exposes its global object on the page. Copies that were concatenated into a single application bundle, renamed, or inlined during a build step do not announce themselves, and those installs are absent from our count. The right interpretation of the number is a lower bound, not a total.

A per-domain lookup answers whether one site uses this library, which is rarely the question anyone actually has. A downloadable list answers the population question instead: which sites still carry HeadJS, in which countries and under which domain extensions they sit, and what else is installed beside it. Filtering and joining that population against the other columns in the export is what turns an obsolete JavaScript libraries into a usable research or prospecting segment, and no amount of one-at-a-time checking will reconstruct it.