Microsoft’s stripped-down Office Online includes Word, Excel, PowerPoint and OneNote. They operate through your browser, and work on Macs too. Anyone with a free Microsoft account can use them, along with 5GB of storage on the OneDrive back-up service, which you can use to store documents.
If you’re used to the Microsoft packages, they’re worth a try, but bear in mind these are hobbled versions of the software. After all, Microsoft doesn’t want to cannibalise its profitable business of selling the full versions of Office.