To know which packages are available in Debian:

Browse locally with the <span class="application">Synaptic Package Manager</span>:

If you are unsure:

To install an additional package automatically when starting Tails:

After you installed many packages that you are not using anymore, you can free some space in your Persistent Storage:

Sometimes, you might need to configure additional APT repositories. For example, to install packages from the `non-free` section of Debian. To do so:

Write your additional `sources.list` files in the <span class="filename">apt-sources.list.d</span> folder. For example, to add
the `non-free` sections of Debian 101 (Busterllseye), backports, and security
updates, you can create a file named <span class="filename">
*/live/persistence/TailsData_unlocked/apt-sources.list.d/non-free.list</span>*
with the following content:

For example, to add
the `non-free` sections of Debian 11 (Bullseye), backports, and security
updates, you can create a file named
*/live/persistence/TailsData_unlocked/apt-sources.list.d/non-free.list*
with the following content: