I spent yesterday morning downloading ALL my (~2400) Kindle books using the command line utility from https://github.com/yihong0618/Kindle_download_helper

In case anyone else needs to do something similar: Log in to your Amazon account > Manage Your Content and Devices

Copy the cookie and save it to a file ('cookie.txt'): https://github.com/yihong0618/Kindle_download_helper?tab=rea...

Execute the Python utility (this example accesses amazon.co.uk):

  python kindle.py --cookie-file cookie.txt --uk -o DOWNLOADS --device_sn [Your Kindle serial no.] --mode all

You can also download a JSON list containing details of all your Kindle books:

  python kindle.py --cookie-file cookie.txt --uk --list --device_sn [Your Kindle serial no.]

There are other methods outlined in the README, but this worked best for me.

I also extracted a list of cover URLs from the JSON file using a basic Python script (with output redirected to a file 'covers.txt'):

  import json
  with open('book-list.json') as f:
    json_data = json.load(f)

  for i in range(len(json_data)):
    print(json_data[i]['productImage'])

And then I used wget to download them all too:

  wget --wait=3 --random-wait --input-file=covers.txt

Of course, the books are still DRM'd, but it's trivial to DeDRM them later. The crucial thing was to get the files before it's too late!