Hi @yoloknight Yes passbolt extension uses a backend API and so it is possible to use passbolt without an extension.
However if you are asking about a browser based access to passbolt that does not use an extension then no, this is not how it works. The extension is actually the component that provides the unique security profile of the app.
It is possible to use the command line to create user accounts. How to create a user manually in cli - #2 by remy for reference, though you will likely need to adjust the commands for your install with respect to the file locations and user permissions.