Download websites that use Kotlin

About Kotlin

Server side languages are close to invisible from outside a web server, and that limitation belongs at the top of this entry rather than buried under it. A visitor receives markup, styles and scripts. The language that produced them leaves at most a trace: a framework cookie name, an unhandled error page, a header a deployment forgot to strip, a build artefact path that survived into production. Kotlin lives entirely in that invisible layer.

JetBrains designed the language to share a runtime with Java, to interoperate with existing Java code, and to remove the null handling and ceremony that made large Java codebases tiring to maintain. Adoption arrived first inside applications rather than on the public web: mobile clients, backend services, build tooling and internal platforms account for most of the code written in it, and none of those surfaces produce a signature that a crawler is entitled to see.

As of October 2026 we associate 17 sites with the language, and the figure is a detection artefact rather than a measure of use. Where an association exists at all, it usually arrives from something a deployment leaked rather than from something the operator chose to advertise. A serving stack written in Kotlin that sits behind a reverse proxy and a content delivery network will expose nothing, so absence from our data is not evidence of absence from the codebase.

Against that limitation the entry is still useful, though for a narrower question than it first appears to answer. Domains that do leak a Kotlin signature tend to belong to organisations that build rather than assemble: engineering led companies, developer facing products, internal tools that were never dressed up for the public. Recruiters, developer tool vendors and infrastructure sellers pay for exactly that filter, because a list of domains where engineers demonstrably work in a named language is a hiring and sales map that no directory of company names can produce.

The language has been public since 2011 and is distributed under Apache 2.0, so a match implies no purchase, no licence and no support contract that anyone could cross reference. A crawl derived list is the closest substitute available, and it is honest only if the undercount is stated rather than hidden.

A per-domain lookup confirms a single site when the signature happens to be exposed, which is the easy case. The export answers the harder questions: how the visible population distributes across hosting providers and markets, how it moves between crawls, and which other technologies sit alongside the language on the same hosts.