Hi @eiro, all packages that you’ve already installed live somewhere in ~/.elm and thanks to this, tools like dmy/elm-doc-preview are able to retrieve their documentation for local usage.
Once installed, you can try the command elm-doc-preview from anywhere and it should open a web page served by a localhost server with the documentation. I also like the --port and --no-browser options.
In addition, if you run elm-doc-preview from an elm project of yours, it will provide the documentation for that project.