Stuff that's free that I talk about:

1. Audacity: https://www.audacityteam.org/

2. Pro Tools First: https://www.avid.com/pro-tools-first

3. Zoom: https://zoom.us/

4. Media.io

5. Your own clothing for soundproofing (no link, and you should be terrified if I offer you one).

6. Your Phone (I... have no link for that either)

7. Audionautix: https://audionautix.com/index.php

8. Freesound.org

9. Pexels.com