Download websites that use Cowboy

About Cowboy

Almost nothing about a website tells you what language the team behind it works in. Cowboy does. Written in Erlang and released under the ISC licence by Nine Nines, it is the HTTP layer that Erlang and Elixir applications reach for when they need to talk to a browser, and a site answering with it has almost certainly been assembled by people who made a deliberate runtime decision rather than picking a hosting plan off a price list.

As of October 2026 we detect Cowboy on 50,054 sites, and the geography says more about infrastructure than about developers. 26,667 of those sites resolve to Netherlands, a share far out of proportion to that country's weight on the general web. Dutch and other northern European providers carry a large amount of platform-as-a-service and bare-metal capacity, and connection-heavy Erlang workloads tend to land there rather than spreading evenly across markets. Reading Netherlands as the home of the companies involved would be a mistake. Domain suffixes point elsewhere, since .com is the suffix these sites use more than any other, which is what you would expect from software businesses selling internationally.

Presence of the server matters because it sits underneath something. A site running it is typically a real-time product, a messaging or streaming backend, an API surface, or a Phoenix application with a marketing front end bolted on. Nobody adopts an Erlang web server to publish brochureware. For anyone selling developer tooling, observability, load testing or Erlang and Elixir consulting, a list of these domains is closer to a qualified pipeline than to a technology census, because the buying group at a shop that runs this stack is small, technical and reachable.

Detection has a real limit here and it is worth stating plainly. The server is normally identified from the banner it returns, and a banner is trivial to strip and frequently invisible behind a reverse proxy or an edge network answering on the origin's behalf. Teams that terminate TLS at nginx or at a CDN will not be counted at all, so the figure above is a floor rather than an estimate of true deployment. Anyone modelling the size of the Erlang web should treat it as such.

What the downloadable list does that a per-domain lookup cannot is let you work in the opposite direction. A lookup answers whether one company you already know about runs this server. The list answers who those companies are, grouped by country, by suffix and by whatever else you join it against, which is the question in front of you when you are sizing a market or building an outbound campaign rather than checking a single account.