Web Accessibility: How to Build Inclusive Web Applications

Over one billion people worldwide live with some form of disability. Web accessibility ensures that people with visual, auditory, cognitive, and motor disabilities can use your applications. Beyond being the ethical requirement, accessibility is increasingly a legal requirement in many countries — and demonstrably improves usability for all users. An accessible website is a better website.

Understanding WCAG 2.2

The Web Content Accessibility Guidelines (WCAG) are the international standard for web accessibility, maintained by the W3C. WCAG 2.2 (the current version) organises guidelines around four principles, forming the acronym POUR: Perceivable (users can perceive all content), Operable (users can operate all interface elements), Understandable (content and interface are understandable), and Robust (content is compatible with assistive technologies).

WCAG has three conformance levels: A (minimum), AA (recommended for most sites), and AAA (enhanced). Legal requirements in the EU, US, and many other jurisdictions mandate AA conformance for public-facing websites.

Semantic HTML Is the Foundation

The single highest-leverage accessibility improvement is using semantic HTML correctly. Screen readers (software used by visually impaired users) navigate content using HTML landmarks and element semantics. A <button> element is keyboard-focusable, announces itself as a button to screen readers, and responds to Enter and Space keypresses automatically. A <div onclick="..."> does none of these things unless you manually add ARIA attributes, keyboard handlers, and role declarations.

Use <nav> for navigation, <main> for primary content, <article> for self-contained content, <button> for interactive controls, and <a href> for navigation links. This alone eliminates a large percentage of accessibility issues.

Keyboard Navigation

Many users navigate entirely by keyboard — people with motor disabilities, power users, and users of screen readers. Every interactive element must be reachable and operable by keyboard. Tab navigates forward, Shift+Tab backward, Enter activates buttons and links, Space toggles checkboxes. Custom interactive components (dropdown menus, date pickers, modals) must implement the correct keyboard interaction patterns as defined by the ARIA Authoring Practices Guide.

Test by unplugging your mouse and navigating your entire application with only a keyboard. Every blocker you encounter is an accessibility failure.

Colour Contrast Requirements

WCAG AA requires a contrast ratio of 4.5:1 for normal text and 3:1 for large text between foreground and background colours. Many popular design choices — light grey text on white backgrounds, subtle placeholder text, thin icon lines — fail this test. Use browser DevTools' colour picker or tools like the WebAIM Contrast Checker to validate all text and icon colours against their backgrounds.

Alternative Text for Images

Every image that conveys information must have descriptive alternative text via the alt attribute. Screen readers read this text aloud in place of the image. Decorative images (background patterns, decorative dividers) should have empty alt="" so screen readers skip them. An AI-generated hero image should have alt text describing what it shows and its purpose on the page.

Automated Testing as a Starting Point

Tools like axe-core (integrated into Chrome DevTools as Accessibility, and available as a Jest/Playwright plugin) automatically catch roughly 30–40% of WCAG violations. Run automated accessibility testing in your CI pipeline. But automated testing is a floor, not a ceiling — the remaining 60–70% of issues require human testing, particularly with actual screen readers (NVDA on Windows, VoiceOver on macOS/iOS).

Conclusion

Accessibility is not a special feature for a special audience. It is good engineering practice that improves your product for everyone. Keyboard navigation helps power users. Good colour contrast helps users in bright sunlight. Semantic structure helps all users orient themselves in complex pages. Build accessibility in from the beginning — it's far cheaper than retrofitting a finished product.