itch.io

Rocky Mountain ADA Center has a great article that reviews the most important information in the WCAG: https://rockymountainada.org/news/blog/twelve-days-web-content-accessibility-guidelines-wcag

https://www.kapwing.com/

Kapwing is my favorite video captioning and transcription tool! The auto captioning is really accurate and very easy to edit. You can do a couple free videos each month, but there are also reasonably-priced subscriptions if you need to caption more videos!

https://colorbrewer2.org/#type=sequential&scheme=BuGn&n=3

Color Brewer was created to improve data visualization (mostly for maps), but it can give you a set of hexcodes based on certain criteria (i.e., colorblind safe, print friendly, photocopy safe, number of hues).

https://contrast-finder.tanaguru.com/

Tanaguru can be used to test your background/foreground colors for appropriate contrast. If your colors don't meet the minimum contrast ratio, it will suggest other colors!

While it's geared toward online content, the Web Content Accessibility Guidelines (WCAG 2.1) provide lots of useful recommendations (and related principles) for all types of media: https://www.w3.org/TR/WCAG21/