This is a short list of tools that I use:
Inkscape – my favorite Open Source vector software, I use it to redraw most of my sketches.
MyPaint – fast and powerful distraction-free painting program that can be used with Wacom tablet, saves .ora and .kra files. I use MyPaint mainly for sketching and brainstorming of ideas.
GIMP – cross-platform image editor, which can be used for both advanced photo manipulation and creation of original artwork. I use it mostly to edit and export existing vector illustrations.
Synfig Studio – open source 2-D animation software. It can import SVG files from inkscape. I’ve been using this program since 2011, because it was the only program I could afford at the time (it’s free), it improved a lot since then.
Vegas Movie Studio 13 Platinum – powerful video editor for reasonable price. I purchased a Steam edition of this software to run it both on my laptop and desktop. When you buy directly from the official site you can use it only on one computer, however when you buy this through Steam you can use it on every computer associated with your Steam account. I use this software to compile JPG images exported from Synfig Studio into HD quality MOV animations.
Marmoset Hexels 2.5 – grid-based drawing and animation software. I’ve tried this software only a few times, but so far I liked what I’ve seen, and I want to incorporate this software into my future work. It can export images into SVG files, so I can edit them in Inkscape and use them in Synfig to create more complicated animations.
Aseprite – simple yet powerful pixel editor, where you can create animated sprites for games or gifs for banners etc.
PyxelEdit – pixel editor, which I use to edit and compile tilesets. I plan to use it for level design in 2D games.
Todoist – productivity and project management software I currently use.