For the holidays, you could say thank you to some of the people who write free software you use, especially software that isn't hugely popular.

Those of us who write little-known software may go for months without hearing from a user, and it can be a little de-motivating.

Hearing from someone who actually uses one's software gives an energising jolt that can carry one through several weeks of darkness and cold and wet.

On Debian-based systems, you can check the /usr/share/doc/foo/copyright file for copyright information for package foo. This roughly corresponds with authorship, especially for smaller projects. The file also usually has a link to the home page of the project or person who produced the software, with contact information.

(See also the this same message on Mastodon.)