Sometime in 2016 we in introduced the concept of "files" to Repl.it, you would click add file and a tab would appear on your Repl. As simple repls grew into full fledged applications and websites tabs started getting ugly and hard to manage.
Moreover, tabs undersold and misrepresented how we deal with files. Your files live in an actual file-system in a Linux machine. For example, you can create and manipulate files from within your code!.
After some design iterations we decided to forgo of tabs completely and stick to a file explorer or a file tree. Now you can view your files in a simple file tree that also includes folders.
We plan on improving the explorer in the future, but for now it has all the basic functionalities that you'd need.