This is a static website that gets autogenerated from a bunch of Joplin notes. I wrote a small script to read the notes, export them, and generate a static site. If you want to use the script and generate such a site for yourself, feel free to fork this repository.
Just run ./joplinexport, it will read the database and create a site like this one and upload it to GitLab pages.
You can see the final site at: