First, David Gaughran posted 12 Free Design Tools for Authors, then Nate Hoffelder at The Digital Reader posted Ten Free Online Image, Graphic, and Photo Manipulation Tools.
PG commends both items to indie authors who are interested in creating graphic designs for promotions, emails, covers, bookmarks (does anyone use those any more?) zippier-looking website posts, etc.
PG also has a few favorite and free/cheap tools of the same type that he enjoys using.
Adobe Spark is a freemium offering from the emperor/empress/queen/king of graphic arts software. PG likes and uses Canva from time to time, but Spark is his current favorite.
Spark offers an always-growing selection of pre-built templates that can provide anyone with a polished, sophisticated graphic design for printing, uploading to any social media service you can think of, dropping into an email, etc.