My research team is building a website that requires the user to input an Excel file with 6 different sheets. Each sheet has a different quantity of data. I understand that to create a file input button, which format can I use. However, I'm not sure how to process the data inside of the Excel file the user inputs?
What language are they building the site in? An upload form is dead easy, there will be examples and tutorials for every web development language and framework. How to access the contents is another matter. Most spreadsheets get converted to a .csv prior to upload so that the data is really easy to handle. A quick google of "PHP excel reader", "python excel reader", or "ruby excel reader" should give you some usable code.