Download websites that use Koa

About Koa

A framework that ships no middleware by default also leaves no fingerprint by default, and the number on this page is the direct consequence of that design. Koa runs on the server. A request arrives, passes through a stack of functions the developer assembled by hand, and a response goes back that looks like any other response. Nothing in that response is required to mention the framework, and in a carefully configured deployment nothing does.

Koa sits in the Web frameworks category, is written in JavaScript and carries the MIT license, with a lineage reaching back to 2013. Frameworks of that generation were shaped around the asynchronous style arriving in JavaScript at the same period, replacing nested callbacks with code that reads from top to bottom. Choosing a framework at that layer says something specific about a team, because they assembled their own request pipeline instead of accepting an opinionated default, which in practice usually means an API or a service rather than a content website.

As of October 2026 we detect Koa on 3 sites, and that figure needs a warning attached to it in plain words. Server side frameworks are systematically undercounted by any method that observes a page from outside. Our detection depends on incidental leakage: a header the operator forgot to strip, a default error page, a distinctive cookie name, an unusual response shape. A production deployment sitting behind a reverse proxy or a delivery network typically leaks none of it. The true population running this framework is larger than what we list by a margin we cannot responsibly estimate, and the extract should be treated as a verified sample rather than as a census.

A verified sample is still worth having, and for this technology it is worth more than a bigger and vaguer estimate would be. Every domain in the set is a place where JavaScript is demonstrably running in production, chosen by somebody who preferred an unopinionated foundation. Developer tool vendors read lists like that to find accounts where their product would install without an argument. Security researchers read them to map exposure when a package deep in the ecosystem turns out to be compromised.

There is no vendor here, because the project belongs to a community rather than a company, so no organisation exists that could hand over the equivalent list even if it wanted to. No version data is recorded either, which is expected for a library that has no reason to announce which release it is. Confirming one site is easy enough on its own. Filtering an entire detected population by market, registry or co installed technology, and then watching which way it moves between refreshes, is the part that needs the file.