Download websites that use Erlang

About Erlang

A programming language is the hardest layer of a website to see from the outside. The browser receives HTML, and HTML looks much the same whether it was assembled by a template engine, a compiled binary or a spreadsheet. Erlang is harder still, because systems built with it usually sit behind a proxy or a load balancer that answers in its own name.

The honest description of what we detect is therefore narrow. We find the language where a server identifies itself in response headers, where a well known service written in it answers on a recognisable path, or where a framework leaves a signature we can match. Deployments that run quietly behind a reverse proxy stay invisible to us. The figure that follows is a floor, and it is biased toward installations that were never configured to keep quiet.

As of October 2026 we detect it on 51,313 sites in the Programming languages category. 26,675 of those are attributed to Netherlands, a concentration that says more about infrastructure than about developers. Language footprints cluster wherever large hosting fleets sit, and a single provider standardising on a messaging broker or a chat server can move a very large block of domains into one country column. Anyone reading the country breakdown as a map of where teams write the language will draw the wrong conclusion from it.

What presence implies about an organisation is unusually strong for a language signal. Nobody inherits this one from a theme or a marketplace install. Created at Ericsson in 1986 for telephone switches that were not permitted to stop, and now released under Apache 2.0, the language gets chosen by teams that have concurrency, uptime or messaging as an explicit requirement. Real time chat, payments, queueing, telecoms and multiplayer infrastructure are where it lands. The engineering culture that comes with those requirements is operations literate and comfortable with distributed systems, which is precisely the buyer profile for observability, on call and infrastructure tooling.

Version data behaves differently here than it does for a plugin. We record 5 distinct release lines, and OTP/26 is the one we see more often than any other, because the platform ships as coarse annual releases rather than a stream of point updates. A release line therefore describes the operating system image and the upgrade cadence of whoever runs the machine more than it describes the application on top. For vulnerability work the coarseness is still useful, since the exposures that matter track the platform release rather than the individual project.

The file earns its keep where a lookup cannot help. Checking one domain confirms that a company you already knew about runs the language. The list answers the questions that need the whole set: which hosting providers carry these deployments, which countries hold real clusters once the infrastructure effect is accounted for, how many domains dropped off between snapshots, and which of them expose a management interface somebody meant to keep private. Recruiters, developer tool vendors and security researchers all want the same thing from this data, which is the population rather than the anecdote.