List open Firefox tabs from the command line?

The format in latest versions is JSON compressed with LZ4 + a magic header (mozLz40\0).

This small python script will print tabs: https://gist.github.com/tmonjalo/33c4402b0d35f1233020bf427b5539fa

The idea would be to access Firefox data from the 'outside'. You might want to look at Stack Overflow question How can I get list of open tabs in Firefox via a command-line application?.

I recommend using https://github.com/balta2ar/brotab for this purpose:

pip install brotab
brotab install

Install the web extension as well: https://addons.mozilla.org/en-US/firefox/addon/brotab/

Restart Firefox, and you can run brotab commands such as:

brotab list