I currently use Google Tasks to manage my to-do list. It's a very simple and basic system, but it suits me just fine. And because I use Gmail for my personal mail, everything integrates nicely.
But when something as important as all my to-do lists are held in the cloud, I like to be able to keep a backup copy on my PC just in case. And while Google provides a method for doing this, via Google Takeout, the data doesn't arrive in a format that's particularly user friendly.
A few days ago I discovered a really neat way of backing up my Google Tasks entries. It's web-based too, so you don't need to download or install anything. Start by visiting https://tasks-backup.appspot.com/ and click on the buttons to authorise the app to access your task lists. Then follow the prompts in order for the app to obtain and download your task lists in the format of your choice. You can get standard text or CSV files, or a nice HTML formatted printable version too.
Personally, I opt for the HTML formatted version, which I keep on my computer just in case Google ever loses my data or decides to deny me access to it.