The Accessibility Testbed is a curated collection of working examples that explore how web accessibility guidelines are interpreted and implemented in practice. With more than 460 test cases, the testbed provides extensive coverage of over 50 success criteria from the Web Content Accessibility Guidelines (WCAG) 2.1, spanning all four principles: Perceivable, Operable, Understandable, and Robust.
It includes foundational requirements like 1.1.1 (Text Alternatives), 1.3.1 (Info and Relationships), and 2.1.1 (Keyboard), as well as more nuanced or recently emphasized criteria such as 1.4.11 (Non-text Contrast) and 4.1.3 (Status Messages). The testbed excludes criteria that cannot be directly implemented or meaningfully demonstrated in code, such as certain synchronized media requirements (e.g., 1.2.4 Live Captions) and guidelines dependent on organizational policy or authoring workflows.
Each example is structured to reveal edge cases, contextual nuances, and variations in behavior across browsers and assistive technologies.
Each test case includes author notes below. These notes represent the author's interpretation of how the example violations could be detected during accessibility testing of real-world websites. Each note is an interpretation and hypothetical. "Automated testing is possible" or "Easy to implement" indicates that the accessibility violation in the test should be detectable with a script or similar automated means. "Hard to automatically test" or "Hard to implement" indicates that detecting the provided violation likely requires a human tester or AI (i.e., an algorithmic tool with near-human detection capabilities) to identify the violation.
This resource is intended for developers, designers, auditors, and toolmakers who need a reliable reference for testing, education, and implementation. All examples are designed to be inspectable, adaptable, and grounded in real-world challenges. Contributions and refinements are ongoing as the platform evolves alongside web standards and accessibility technologies.