Our team is in contract with a company that has put a few constraints due to security reasons. We work in their offices, and our computers (provided by that company) at work are monitored by their network security system and the Internet is tightly monitored as well. In addition, excel, word, pdf, text, and many other files are encrypted.

We share an Excel file to keep track of our work in progress. This excel file is stored in a folder which is located in a server that the company specifically gave us the permission to access.

Only pipeline in which we can share any files or data is via that specific folder across the network which is only accessible by us.

My goal is to make a browser-based application that mimics what is being done on the excel file, but the constraints for this application are that, it cannot be an external web application where data is sent via the Internet and stored externally, and we cannot have any of our own physical computer to be made as a server, and they cannot provide us with a local machine to serve a web application.

My question is, is it possible to make a stand-alone browser-based application that can run without a server, and still be able to store data in [nosql,sqlite,text file,json,etc.], which many people can access at the same time? If yes, what are some tools that are usually recommended for this purpose?

I'd really appreciate your help, thanks!