Learn how to share your Excel Workbook across the web with others. You can do all the sharing via cloud apps like OneDrive right from within Excel.

Check "Recipients can edit" and click the "Share" button. Click on the Excel "File" tab. Click the "Open in Excel" option to launch your desktop version of Excel.

Google Sheets is free and easily allows multiple users to collaborate in a spreadsheet in real time, but it's also fairly simplistic.