If you want to use online Office tools but do not want to upload your documents to the servers of Microsoft, then you can try something called CryptPad. It is an open-source Office Suite designed with privacy and encryption in mind. Designed to be highly private, CryptPad could prove to be a popular alternative to other Office web apps and cloud services. All the content stored on CryptPad is encrypted before being sent, which means nobody can access your data unless you give them the keys.
CryptPad is open-source and anybody who has a web server can host CryptPad on their own domain name. This is what makes it private since you are keeping all the data on your own web server. Using the domain or sub-domain, you can access CryptPad and use it from anywhere in the world. Installation can be done only on a Linux or FreeBSD server.
CryptPad is an open-source software and can be installed anyone who wants to use or provide its services. For example, an organization or company can install it for their students or employees.
CryptPad offers two types of user accounts – guest accounts and the logged in accounts. Guest users do not need to create any account and can use all the CryptPad features. But the documents that they create will be available only for 3 months from the last modification.
The logged in users are the users with a registered user account which can be created only using a username (if available) and password. These users are given personal and permanent storage for their documents.
One of the instances of CryptPad, https://cryptpad.fr/ also offers premium paid user accounts. These users get extra storage space, larger file size allowed to be uploaded, and priority support/help from the administrators.
You can find public online instances of CryptPad at https://cryptpad.org/instances/. Source code of CryptPad is available from GitHub at https://github.com/cryptpad/cryptpad.