Accessibility in Web Development: A Complete Guide

Web accessibility isn't a nice-to-have—it's essential. Over 1 billion people worldwide live with some form of disability. When we build inaccessible websites, we exclude potential customers, expose our organizations to legal risk, and miss opportunities to create better products for everyone. This guide covers what you need to know to build truly accessible web applications.

Why Accessibility Matters

The Business Case

• Market size: People with disabilities represent $8 trillion in annual disposable income globally
• Legal compliance: Laws like ADA, Section 508, and EAA require accessible digital experiences
• SEO benefits: Many accessibility practices improve search engine optimization
• Better UX for all: Accessible design benefits everyone—captions help in noisy environments, keyboard navigation helps power users

Types of Disabilities to Consider

• Visual: Blindness, low vision, color blindness
• Auditory: Deafness, hard of hearing
• Motor: Limited fine motor control, paralysis, tremors
• Cognitive: Learning disabilities, attention disorders, memory impairments
• Temporary/Situational: Broken arm, bright sunlight, loud environment

Understanding WCAG

The Web Content Accessibility Guidelines (WCAG) are the international standard for web accessibility. They're organized around four principles (POUR):

1. Perceivable

Users must be able to perceive the information being presented. It can't be invisible to all their senses.

2. Operable

Users must be able to operate the interface. The interface cannot require interaction that a user cannot perform.

3. Understandable

Users must be able to understand the information and operation of the interface.

4. Robust

Content must be robust enough to be interpreted by a wide variety of user agents, including assistive technologies.

Conformance Levels

• Level A: Minimum accessibility
• Level AA: Addresses major barriers (most common target)
• Level AAA: Highest level of accessibility

Essential Accessibility Practices

Semantic HTML

Use HTML elements for their intended purpose. Screen readers rely on semantic structure:

• Use <header>, <nav>, <main>, <footer> for page structure
• Use <h1>-<h6> in logical order for headings
• Use <button> for clickable actions, <a> for navigation
• Use <ul>/<ol> for lists, <table> for tabular data

Keyboard Navigation

All functionality must be accessible via keyboard:

• Tab should move through interactive elements in logical order
• Enter/Space should activate buttons and links
• Escape should close modals and dropdowns
• Arrow keys should navigate within complex widgets
• Focus indicators must be visible (never outline: none without alternative)

Focus Management

• Maintain logical tab order (avoid positive tabindex values)
• Move focus to modals when opened, return when closed
• Trap focus within modal dialogs
• Announce dynamic content changes to screen readers

Alternative Text

Images need appropriate alt text:

• Informative images: Describe the content and function
• Decorative images: Use empty alt (alt="")
• Complex images: Provide detailed descriptions nearby
• Functional images: Describe the action (e.g., "Search", "Submit")

Color and Contrast

• Text contrast ratio: 4.5:1 minimum (3:1 for large text)
• Don't rely on color alone to convey information
• Ensure links are distinguishable from surrounding text
• Test with color blindness simulators

Forms

• Every input needs a visible <label> associated with for/id
• Group related fields with <fieldset> and <legend>
• Provide clear error messages that identify the field and describe the error
• Don't rely on placeholder text as labels
• Support autocomplete attributes for common fields

ARIA: When HTML Isn't Enough

ARIA (Accessible Rich Internet Applications) adds semantic information for custom widgets. Follow the first rule of ARIA: Don't use ARIA if native HTML can do the job.

Common ARIA Patterns

• aria-label: Provides accessible name when visible text isn't available
• aria-labelledby: Points to element(s) that label this element
• aria-describedby: Points to element(s) with additional description
• aria-expanded: Indicates expandable content state
• aria-hidden: Hides elements from assistive technology
• role: Defines what an element is (use sparingly)

Live Regions

Announce dynamic content changes:

• aria-live="polite": Announce when convenient (most common)
• aria-live="assertive": Announce immediately (use for errors)
• role="alert": Shorthand for assertive live region
• role="status": Shorthand for polite live region

Testing for Accessibility

Automated Testing

Catches about 30-40% of issues:

• axe DevTools: Browser extension for page analysis
• WAVE: Visual accessibility evaluation tool
• Lighthouse: Built into Chrome DevTools
• jest-axe: Automated testing in CI/CD

Manual Testing

Essential for comprehensive coverage:

• Navigate entire site with keyboard only
• Test with screen readers (VoiceOver, NVDA, JAWS)
• Zoom to 200% and check layout
• Test with browser zoom and text-only zoom
• Verify in Windows High Contrast Mode

User Testing

Nothing replaces testing with actual users who rely on assistive technology. Include people with disabilities in your user research.

Common Accessibility Issues and Fixes

Missing Form Labels

<!-- Bad -->
<input type="email" placeholder="Email">

<!-- Good -->
<label for="email">Email</label>
<input type="email" id="email">

Non-Descriptive Links

<!-- Bad -->
<a href="/pricing">Click here</a>

<!-- Good -->
<a href="/pricing">View pricing plans</a>

Missing Skip Links

<!-- Add at top of page -->
<a href="#main-content" class="skip-link">
  Skip to main content
</a>

Inaccessible Custom Components

If you build custom dropdowns, modals, tabs, or other widgets, follow WAI-ARIA Authoring Practices for proper keyboard interaction and ARIA attributes.

Building an Accessible Culture

• Shift left: Include accessibility in design and development from the start
• Training: Ensure designers and developers understand accessibility basics
• Design system: Build accessibility into reusable components
• Acceptance criteria: Include accessibility requirements in tickets
• Regular audits: Schedule periodic comprehensive accessibility reviews

Conclusion

Accessibility is both a moral imperative and a business opportunity. By building accessible products, you expand your market, reduce legal risk, and create better experiences for everyone. The practices outlined here aren't exhaustive, but they cover the most impactful areas.

Start with semantic HTML, ensure keyboard accessibility, provide text alternatives, and test with real assistive technology users. Accessibility isn't a checklist to complete—it's an ongoing commitment to inclusive design.