How to Validate and Test HTML Before Release
Combine conformance checks, keyboard testing, responsive review, performance measurement, and content verification.
The short version
Validation catches markup errors; testing catches experience errors.
Run an HTML conformance check
A validator can catch duplicate ids, invalid nesting, missing required attributes, and obsolete markup. Fix errors first, then review warnings in context. A valid page can still be inaccessible or confusing, but invalid structure makes every later check harder.
Test the human paths
- Read the page at 200 percent zoom.
- Navigate with Tab, Shift+Tab, Enter, Space, and Escape.
- Use a screen reader for the main route and form.
- Test the smallest supported viewport.
- Check loading, empty, error, and success states.
- Verify every factual claim and destination.
Keep a release checklist close to the artifact
Record what was tested, by whom, and against which version. When a comment reveals a problem, add the missing check to the template so the next page benefits.
Automated tools are valuable for repeatable regressions. Human review remains essential for reading order, clarity, visual hierarchy, and whether the page fulfills its purpose.