Excel has never been free. It's been bundled with Microsoft Office that's sometimes included in the purchase price of a computer but it has most definitely not been free! (Danny's link goes to a
trial version, as shown in the 'Product details' column). The only freebie offered by Microsoft is Excel Viewer which, as the name suggests, allows you to view Excel spreadsheets but not to create or edit them.
As CrapAtCryptics states, OpenOffice Calc (which is part of the full OpenOffice suite) does everything that Excel does. (Indeed, it handles some of the very large spreadsheets that I download from research sources rather better than Excel does):
https://www.openoffice.org/
The only thing you need to note about OpenOffice programs is that, by default, they save files in non-Microsoft formats (meaning that people using Microsoft Office won't be able to view them). You can get round that simply by using 'Save As', instead of 'Save', and selecting a suitable format. It's better though to change the default settings, so that your OpenOffice programs automatically use Microsoft formats. Their are easy instructions here:
http://helpdeskgeek.com/office-tips/set-openof%EF%AC%81ce-org-to-save-in-microsoft-of%EF%AC%81ce-format-by-default/