I had a somewhat similar requirement in a past work. The Excel file had all the formulas and data, and the analysts only work with Excel files. The result of

I had a somewhat similar requirement in a past work. The Excel file had all the formulas and data, and the analysts only work with Excel files. The result of the calculation in Excel needed to be put on the web. The solution was not to recreate Excel in the browser, but ran the Excel file with its formulas and its data plus the input parameters from end users at the backend server. Apache POI was a nice Java library that could do everything on an Excel file. Once it finished the formula calculation, I just read the cells from the Excel file to extract the result data and generated the web pages to present the data and graphs. One nice benefit was the analysts could update their work in the Excel file, uploaded it to the server, and got the new calculation reflected on the web pages right the way.