@utikeev can you debug the traffic and then reproduce with curl?

Oh, well. It seems like my bad, as I forgot to open connection for the URL I'm using.

which HTTP client are you using? You probably shouldn't be needing to open url connections unless you're writing an HTTP client!

Well, I use

Fuel

in a string-extension way. It seems they use their own: https://github.com/kittinunf/Fuel/blob/master/fuel/src/main/kotlin/com/github/kittinunf/fuel/toolbox/HttpClient.kt

@utikeev - Sounds like Fuel isn't properly tested/mature. At this point I would recommend going with OkHttp (http://square.github.io/okhttp/). If you have used Vert.x before then the vertx-web-client (http://vertx.io/docs/vertx-web-client/kotlin/) is another good option with solid Kotlin support.

Probably not worth pulling vert.x as a dependency for a simple HTTP call

Cedric - True unless vertx-core is used in the project, or the project relies on a server side project written using Vert.x.