What is WCAG 2.1?
The Web Content Accessibility Guidelines (WCAG) 2.1 are an international W3C standard defining how web content should be made accessible to people with disabilities. Austria's BFSG requires conformance with WCAG 2.1 Level AA.
WCAG is structured around four principles (abbreviated POUR):
1. Perceivable
All information and UI components must be presented in a way that users can perceive.
Most common errors:
- Missing alt texts (Success Criterion 1.1.1): Images without alternative text cannot be interpreted by screen readers. _Solution: Every content-bearing image needs a descriptive alt text._
- Insufficient color contrast (1.4.3): Contrast ratio must be at least 4.5:1 (text) or 3:1 (large text). _Solution: Use a contrast checker (e.g., WebAIM Contrast Checker)._
- Videos without captions (1.2.2): Recorded video content requires captions. _Solution: Enable captions on YouTube/Vimeo or embed SRT files._
2. Operable
UI components and navigation must be operable.
Most common errors:
- No keyboard accessibility (2.1.1): All functionality must be reachable by keyboard. Test: Navigate through the page using Tab — are all interactive elements reachable?
- No visible focus indicator (2.4.7): The currently focused element must be visible. Many CSS resets remove the browser's default ':focus' outline — this is problematic.
- Too short time limits (2.2.1): If sessions expire, users must be warned and given the opportunity to extend the time.
3. Understandable
Information and the operation of the user interface must be understandable.
Most common errors:
- Missing language declaration (3.1.1): The HTML tag must have the 'lang' attribute: ''. Screen readers use this for correct pronunciation.
- Unclear error messages (3.3.1): Forms must clearly describe what's wrong ("Please enter a valid email address" instead of "Error").
- Missing labels for form fields (1.3.1): Every input field needs an associated '
4. Robust
Content must be robust enough to be interpreted by various user agents.
Most common errors:
- Invalid HTML (4.1.1): Faulty HTML structure (duplicate IDs, incorrectly nested elements) can confuse assistive technologies.
- Missing ARIA attributes (4.1.2): Interactive custom elements need correct ARIA roles and properties.
Top 5 Errors from WebAIM Million Report 2024
According to the annual analysis of one million websites, the most common errors are:
1. Low color contrast (81% of websites!)
2. Missing alt texts (54%)
3. Missing form labels (48%)
4. Missing document language (18%)
5. Missing button texts (28%)
Conclusion
WCAG 2.1 Level AA is achievable — with a systematic approach. Automated scanning can detect 30-40% of all issues. The rest requires manual testing (keyboard navigation, screen reader testing).
Use BFSG-Scan.at for an initial assessment — free in 60 seconds.