An HTML validator is a tool that checks a web page's code for errors and problems with its structure and semantics. Accessibility validators, often available as browser extensions, also flag issues likely to affect assistive technology users.
Why it matters: Correct, well-structured HTML is the foundation that screen readers and other assistive technologies rely on. Validators give a fast first pass that catches structural problems before manual testing starts.
In practice: Testers run a validator against a page, review what it flags, and use the results as a starting point rather than a verdict. Some flagged issues aren't real failures, such as duplicate IDs that only appear in code comments, or code that isn't active. When results are unclear, reviewing them with a developer helps separate real problems from noise.
Examples:
- Running a browser extension on a page to find missing labels and duplicate IDs before manual testing.
- Reviewing flagged issues with a developer to rule out false positives.
Common pitfalls:
- Treating a clean validator report as proof that a page is accessible.
- Spending time fixing flagged issues that don't affect users at all.
Can an HTML validator replace accessibility testing? No. It catches code-level problems, but it can't tell whether content makes sense when read aloud, whether navigation is logical, or whether real users can complete a task.
