The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Use an HTML validator when you want to check a document against HTML syntax and related conformance rules; use an editor-integrated linter when you want diagnostics as you write. The labels overlap, though, so the practical question is what rules a tool checks and where it reports problems. Neither a passing result nor the word “validator” proves that a page is fully accessible or conformant.
What is the difference between an HTML linter and a validator?
An HTML validator checks markup against defined syntax or specification rules and reports discrepancies. A linter is a broader kind of development tool that surfaces diagnostics during editing or a build. In everyday use, linting often emphasizes fast feedback in the authoring workflow, while validation emphasizes checking a document against a defined standard.
These are not exclusive technical categories. The W3C Markup Validation Service describes its validator as “sort of like lint for C.” A checker may therefore perform validation and serve a lint-like role. Compare a tool’s documented checks and workflow rather than relying on its label.
What can an HTML checker tell you?
A validation result tells you whether the checker found discrepancies within the rules it applies. The W3C explains that validity concerns markup syntax against a defined grammar, while conformance can include requirements that the grammar cannot express. A valid document is not automatically a fully conformant one.
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The Nu Html Checker documentation notes that errors can signal possible accessibility, usability, interoperability, security, maintainability, performance, parsing, or scripting problems. These are warning signs worth investigating, not a complete assessment of those qualities. The project also cautions that the checker is intended as a checker, not a pass/fail certification mechanism.
Which tool should you choose?
| Your need | Start with | Why |
|---|---|---|
| Check a document’s HTML syntax and catch markup issues | A validator or checker, such as the Nu Html Checker | It is explicitly presented as an HTML checker and validator. |
| See feedback as you edit in Visual Studio Code | An editor-integrated linter, such as HTMLHint | HTMLHint advertises real-time feedback through its VS Code extension. |
| Automate document checks in a build or service workflow | A checker with an appropriate command-line or service interface | The Nu project describes command-line and HTTP service modes. |
| Determine whether a page meets accessibility requirements or fully conforms to a specification | Validation plus separate assessment of the relevant requirements | Validation alone does not necessarily test full conformance. |
For a quick online check, the W3C tools directory lists the Nu HTML Checker. For ongoing feedback, choose an editor tool that fits your setup. For automation, confirm that the checker’s interface and configuration fit your build or service. These are workflow examples, not a ranking: the tool’s actual rules and the result you need matter more than its name.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Does passing validation mean the page is accessible?
No. Validation can reveal markup issues relevant to accessibility, but it does not establish that every accessibility requirement is met. The W3C WAI technique G134 treats validation as an automatic check against a specification, not sufficient proof of accessibility conformance. Assess the applicable accessibility requirements separately.
Quick Recap
How should you interpret validation results?
- Read each finding in context. A reported error may point to a potential problem; it is not, by itself, a full evaluation of the page’s behavior or quality.
- Check the scope of the rules. “Valid” means the document passed the checks applied by that tool, not that every requirement outside its grammar was tested.
- Recheck important documents when needed. The Nu Html Checker documentation says checks are actively added and does not guarantee identical results for the same document at different times. A result is tied to the checker’s behavior when you run it.
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