Accessibility == Usability. From MDN:

Accessibility is the practice of making your websites usable by as many people as possible. We traditionally think of this as being about people with disabilities, but the practice of making sites accessible also benefits other groups such as those using mobile devices, or those with slow network connections.

Making an accessible website is not just checking requirements to comply to a standard, it’s a natural extension of UX design: we must design our software in a way that works for everyone.

Although official standards are well-documented, best-practice design patterns are much less standardized, hence many useful resources have been authored by individuals.

Standards / specs

The W3C Web Accessibility Initiative (WAI) is the de facto standards body for web accessibility. Their website contains loads of resources: tutorials, guides, articles, specs, and more about the how/what/why of accessibility.

• Web Content Accessibility Guidelines (WCAG)
  These are the criteria that accessible web apps are expected to meet.

  • WCAG 2.2 Spec

  • WCAG Quick Reference
    Condensed list of all criteria (filter by level A, AA, or AAA)

• Accessible Rich Internet Applications (WAI-ARIA)
  A set of HTML roles and attributes to improve accessibility.

  • WAI-ARIA 1.2 Spec

  • WAI-ARIA Authoring Practices Guide (APG)
    Explains how to implement various components and design patterns, with reference implementations.

    • ARIA APG raw text
      Same info as above but formatted as a single-page spec, rather than a multi-page website. This version is harder to read but easier to search through.

Web Accessibility best practices by Level Access
Checklist for an accessibility audit, which includes all WCAG 2.1 criteria.

General guides / resources

• MDN Accessibility Reference and Accessibility Guide
  Comprehensive technical info about all the web technologies.

• Accessible to all by web.dev

• Microsoft Inclusive Design
  Resources aimed at designers, with a lot of background and examples about how inclusive thinking benefits different people.

• The a11y project
  An independent organization with lots of blog posts and other resources, aggregated from around the web. They also have an email newsletter, which is a good way to be fed a small amount of info on a regular basis

• A11y Style Guide by Carie Fisher
  Easy-to-read overview, with lots of resources linked.

How to self-audit

Interacting with your application in different ways as you develop it will help uncover usability issues. Here are some easy checks that anyone can do without special training:

• Try using the site with only the keyboard. You should be able to access all the same information and perform the same actions that a mouse user can.

• Inspect the semantics of the Accessibility Tree (AT) in the Chrome devtools. Screen readers and other assistive technologies view the site via the information in the AT. The contents of this tree should make sense semantically.

• Try navigating the site using a free screen reader (VoiceOver on Mac or NVDA on Windows). It should convey all the same information as what's on the screen.

• Run an automated checker such as axe, which is available as a browser extension, via the Lighthouse audit in the Chrome devtools, or as an NPM package.

• Increase the text size to 200% using the browser's built-in zoom function. The layout should still be usable.

The following articles explain these (and other easy checks) in more depth:

• https://www.w3.org/WAI/test-evaluate/preliminary/

• https://web.dev/how-to-review/

Courses / Trainings

• Learn Accessibility by web.dev (Google)
  20-chapter series of articles (a.k.a. "self-paced course"), written by Carie Fisher.

• Web Accessibility on Udacity (by Google)
  Free online course. Summarized in this article.

• A11ycasts by Rob Dodson
  30-part YouTube playlist. Most of the videos are between 5 and 15 minutes long.

• Testing Accessibility by Marcy Sutton
  Paid 6-part course on building accessible web apps through the entire lifecycle: design, build, test, ship.

• Practical Accessibility by Sara Soueidan
  Paid video course. Looks to be more focused on the technical nuts-and-bolts than Marcy Sutton's course.

Conferences / Meetups

• A11y Talks
  A “virtual meetup” consisting of over 60 recorded talks. Hard to browse via their site; easier via their YouTube channel.

• axe-con
  A free conference run by Deque Systems (accessibility consultancy and makers of axe).

  • Despite being an advertisement for Deque’s products, the conference contains lots of useful talks.

  • Recordings of past years can be watched for free, if you register.

• Global Accessibility Awareness Day
  3rd Thursday in May each year - Miscellaneous events are held around the world

Component libraries

These component libraries claim to conform to WCAG standards; they could act as good reference implementations.

https://www.digitala11y.com/accessible-ui-component-libraries-roundup/

Influencers

Lots of helpful information about accessibility is written by independent people who have figured stuff out and shared their knowledge on personal blogs. These people have good things to say.

• Carie Fisher (website) (twitter)

  • A11y writer/speaker

  • Creator of A11y Style Guide and A11y Talks virtual meetup

• Marcy Sutton (website) (twitter) (”Testing Accessibility” blog)

  • Freelance a11y specialist

  • Free email list with interesting weekly mini-articles (which are informative, but are also ads for her workshops)

  • Conducts regular online workshops (see “Services” tab or https://testingaccessibility.com/workshops)

• Ben Myers (website) (twitter)

  • Accessibility advocate with a weekly livestream, and also a blog

• Scott O’Hara (website) (twitter)

  • Accessibility developer at Microsoft

• Adrian Roselli (website)

  • Consultant with lots of deep-dive blog articles about specific topics and pitfalls

• Sara Soueidan (website) (twitter)

  • She’s developing a paid online course, set to debut in early 2023

• Sarah Higley (website)

• Ashlee M Boyer (website)

Miscellaneous Articles

Various one-off pieces I found especially useful.

• https://www.sarasoueidan.com/blog/focus-indicators/

• https://cariefisher.com/a11y-start/

• https://mikemai.net/blog/2022/12/04/24-semantic-terms-web-pros-should-know.html

• https://css-tricks.com/inclusively-hidden/

• https://css-tricks.com/making-disabled-buttons-more-inclusive/

• https://www.tpgi.com/using-the-html-title-attribute-updated/

• https://medium.com/salesforce-ux/7-things-every-designer-needs-to-know-about-accessibility-64f105f0881b

Consultancies

These companies can be hired to do accessibility audits for your software. Their websites also contain lots of educational material about how to conform to the various standards.

• https://axesslab.com/
  They have a nice blog too!

• https://www.levelaccess.com/

• https://www.deque.com/

Advice threads / aggregations of resources

Dropping these links here so I can find them in the future; likely some interesting resources in these threads that could be listed above.

• https://twitter.com/codeability/status/1504608001877020676?s=21

• https://a11y-style-guide.com/style-guide/section-resources.html

• https://twitter.com/kathryngrayson/status/1565401468714323971