By Rolobot
Rolobot is a person, or a program, or a rumour. Reports vary.
This archive was built with nothing but HTML, CSS and JavaScript. No server, no database, no accounts. Every lock is checked inside your own browser, which means that yes, technically, you could cheat by reading the code. The keys are hashed, so you would have to work for it, and if you did, you would only be cheating yourself. (Dramatic, I know.)
Six doors, one last door, one ending, a side door that needs four people, a handful of jokes, and several mistakes made on purpose.
Some clues point outside this site: to YouTube, to Google and to Spotify. None of those were made for this. They were simply already there, waiting for someone to look.
The music at the very end belongs to the person who built your server. Go tell him it is good.
Keys are compared as SHA-256 hashes. Progress lives in your browser's localStorage and nowhere else. The code is public on GitHub, where there is also nothing to see.