WCAG 2.1 Requirements Checklist

The Web Content Accessibility Guidelines (WCAG) 2.1 at the AA conformance level comprise 50 success criteria organized under four principles — Perceivable, Operable, Understandable, and Robust. Each criterion describes a specific requirement that web content must meet to be accessible. Understanding the full scope of requirements is essential for planning remediation, because many organizations underestimate the breadth of WCAG. Here is a summary by principle:

• Perceivable (28 criteria at A+AA): Content must be presentable to all users. This covers text alternatives, time-based media, adaptable content, and distinguishable elements (contrast, resize, spacing, reflow)
• Operable (15 criteria at A+AA): Interface must be navigable. This covers keyboard access, enough time, seizure prevention, navigability, and input modalities
• Understandable (5 criteria at A+AA): Content and UI must be understandable. This covers readable text, predictable behavior, and input assistance
• Robust (2 criteria at A+AA): Content must work with assistive technologies. This covers parsing and name/role/value for UI components

While all 50 criteria matter, some are more frequently violated and more impactful than others. Here are the requirements most often flagged in audits:

• 1.1.1 Non-text Content (A): All images, icons, and media need text alternatives. The most common violation is <img> tags without alt attributes
• 1.4.3 Contrast Minimum (AA): Normal text needs 4.5:1 contrast; large text needs 3:1. Found on 81% of homepages
• 1.4.10 Reflow (AA): Content must reflow at 320px width without horizontal scrolling — critical for mobile
• 2.1.1 Keyboard (A): All functionality available via keyboard. Custom dropdowns, modals, and tabs frequently fail this
• 2.4.7 Focus Visible (AA): Keyboard focus must have a visible indicator. CSS outline: none without replacement breaks this
• 3.3.2 Labels or Instructions (A): Form inputs need programmatically associated labels, not just placeholder text
• 4.1.2 Name, Role, Value (A): Custom UI components must expose their name, role, and state to assistive technology via ARIA

Of the 50 WCAG 2.1 AA success criteria, automated tools can fully test approximately 15-20 and partially test another 10-15. Here is how they break down:

• Fully automatable: Contrast ratios (1.4.3), missing alt attributes (1.1.1), missing form labels (3.3.2), duplicate IDs (4.1.1), language of page (3.1.1), ARIA validity (4.1.2 partially), heading hierarchy (1.3.1 partially), link purpose from text (2.4.4 partially)
• Partially automatable: The tool can flag potential issues but a human must verify. For example, alt text presence is automatable but alt text quality is not. Tab order can be flagged but logical correctness requires human judgment
• Manual only: Meaningful sequence (1.3.2), captions for live audio (1.2.4), audio description (1.2.5), error suggestion quality (3.3.3), consistent navigation across pages (3.2.3)

CompliScan automates everything in the first two categories, giving you a head start on the most common and most impactful violations before you invest in manual review.

Instead of working through a 50-item checklist manually, let CompliScan automate the machine-testable requirements. Here is how to use the two together:

1. Run a free scan on your most important page (usually your homepage or main conversion page). CompliScan tests against all automatable WCAG 2.1 AA criteria and returns a prioritized violation list
2. Review results by WCAG criterion: Each violation is mapped to its specific success criterion number (e.g., 1.4.3, 2.1.1). Cross-reference with this checklist to understand the requirement
3. Apply AI fix suggestions: CompliScan generates specific code changes for each violation — copy, adapt, and deploy
4. Manual review: Use this checklist to test the criteria that automated tools cannot cover. Focus on keyboard navigation flow, screen reader experience, and content clarity

Paid plans add continuous monitoring: Shield ($49/mo) for weekly scans of 3 sites, Shield Pro ($149/mo) for daily scans with PDF reports, and Agency ($299/mo) for 50-site coverage.