Use Calibre to Back Up Your Kindle Books Before February 26
Amazon just announced that you have until February 26, 2025, to download your Kindle content. After that date, you will no longer be able to access the books you've paid for if you have a legacy device or a Kindle that has experienced wireless issues. The only way to load what you've paid for onto a device will be through wireless sync.
Thankfully, using the free ebook manager, Calibre, you can convert your Kindle content into formats readable on other ebook readers or into PDFs. You will be protected if Amazon ever removes books you've paid for. You do not need to download the Kindle app on your Mac to accomplish this.
Log in to your Amazon account. In the account section, select Content Library>Books. You'll have to download each title you want to back up as a separate files in azw3 format.
Download Calibre directly from the developer. To gain the ability to convert the books into other formats using Calibre, you will need to download a plugin from GitHub.. Make sure to install and set up the plugin before importing your books into Calibre. You will need the serial number from your Kindle to do this. You can get this information from the Amazon website or from the device itself.
For detailed instructions, see this article.