Software as a Service
Software is NOT a service. Almost any service that you're not paying for is using you to make money somehow. Almost always, this is through advertisements, that use a large amount of trackers to better target them to you. Having these trackers is a serious threat to your privacy. Also, since most software services are anything but free software, you have no real idea as to what they're doing with the data you give them, or what data they're taking on their own.
The biggest offenders in this regard are Google, Amazon, and Facebook. If you're using their services, you shouldn't be.
switching.social offers a simple guide on replacing Google and other offenders.
The general exception to this is free software, especially federated or decentralized free software. See: /f/freeAsInFreedom
Alternatives to Services
Diaspora - Alternative for Facebook
Tutanota - Alternative for Gmail
write.as - Alternative for Medium
Pixelfed - Alternative to Instagram
OpenNMT - Alternative to Google Translate (More limited in languages)
See Internet Browsing.