AccessGuide A very useful resource with ‘Accessibility Cards’. Just pick a card and learn more about accessibility guidelines of your interest.
Accessibility.VoxMedia Another useful accessibility checklist.
AreMyColorsAccessible A handy tool to check if a combination of colors is accessible.
Inclusive-Components.Design A very useful resource blog with accessibility concepts. It has not been updated for a while, but still, it’s a great resource.
UXmyths A list of UX misconceptions.
w3.org The World Wide Web Consortium. It’s the main international standards organization for the web.
w3.org checklist One of the most popular industry-standard accessibility checklists.
Webaim.org A non-profit organization focusing on web accessibility