uMatrix

Definitely for advanced users. uMatrix does not guarantee that sites will work fine: it is for advanced users who can figure how to un-break sites, because essentially uMatrix is a firewall which works in relaxed block-all/allow-exceptionally mode out of the box: it is not unexpected that sites will break. uMatrix can be set to work in allow-all/block-exceptionally mode with a single click on all cells in the global scope if you prefer to work this way. This will of course break fewer sites, but you would then lose all the benefits which come with block-all/allow-exceptionally mode, though you will still benefit from the 62,000+ blacklisted hostnames by default. HTTP Switchboard's documentation is still relevant, except for uMatrix's differences with HTTP Switchboard.