After a while, you need to be able to back up your Mastodon content, and there is currently no way to get anything except your follow/block/mute lists.
This tool downloads all your posts it finds via the public Atom feed. Sadly, these are not all of your posts, due to a bug. You will have to resort to screen scraping in order to do this. A better alternative would be to use the Mastodon API to get all of your toots (thus requiring a login). Mastodon Backup does that, for example.
The tool allows you to turn the aggregated Atom feed into a web page. The web page will not contain any media attachments, avatars or any of that. Mark's Mastotool mirrors media.
If you still want to give it a try: you need Python 3 and lxml:
% sudo pip3 install lxml
Usage:
% ./Mastotool.py -help
Usage: Mastotool.py [COMMAND]...\n%s
--backup URL Backup from URL 'http://example.com/@username'
--load FILENAME Load from Atom file
--display Display all posts as text
--html Display all posts as html
--save FILENAME Save to Atom file
To make a backup:
% ./Mastotool.py --backup http://example.com/@username --save username.atom
To display that backup:
% ./Mastotool.py --load username.atom --display
To generate a HTML file:
% ./Mastotool.py --load username.atom --html > username.html
Please only use this on your own data.