There are dozens upon dozens of resources on accessibility, but these are some of the easiest to digest and a great way to start digging in.
Checklists and Guides:
- A11Y Project Accessibility Checklist – a FANTASTIC checklist to reference to help you hit all the quick wins. The rest of the A11Y Project site is pretty stellar, too.
- 18F Accessibility Guide provides an overview of requirements and a wealth of tools to help you dig in.
- WuhCAG provides plain language checklists of WCAG standards
Color Contrast:
- Tanaguru Contrast-Finder – checks your color contrast and provides close alternates that meet the guidelines.
- Contrast-Ratio – a lovely way to test color contrast, including opacity, and tweak settings yourself
- WebAim Contrast Checker – when you want to keep it simple. Tests against both normal and large font sizes.
Do it With Drupal:
- Documentation: Accessibility tools and best practices for site builders is an overwhelming list of tools for Drupal site builders.
- D8 is serious about accessibility – take the pledge to build accessible with #D8AX
- Drupal Accessibility group
Simulators
- VisionSim lets you see the world through a simulation of vision disabilities (look it up -available for iOS and Android)
- NoCoffee Vision Simulator for Chrome lets you view the web through a filter
Accessibility Checkers
- Pa11y – free, open source, self-managed accessibility testing suite