HTML-validate – offline HTML5 validator

HTML-validate is an offline HTML validator designed for both complete documents and HTML fragments used by component-based frameworks.

Validation is performed locally. It uses strict parsing rather than attempting to repair malformed markup and provides extensive rules covering HTML syntax, document structure, permitted content, forms, accessibility and best practices.

HTML-validate can process HTML embedded in other source files through transformers. It supports configurable rule sets, shareable configurations, plugins, custom element metadata and both traditional and flat configuration files.

The supplied presets include standards-focused validation as well as a broader recommended configuration covering HTML standards, accessibility and good development practices. Many problems can be automatically fixed where a rule supports it.

This is free and open source software.

Key Features

• Fragments and components:
  • In addition to validating plain .html files HTML-validate can also validate sources inside .js components (or any other source) by extracting HTML fragments (transforming).
  • Neither .html files or component fragments need to be a complete document (e.g. doctype is not required).
  • Transformed sources can also be postprocessed to handle data-bindings from different frameworks, e.g. :id will still be understood the same way id would.
• Offline – Does not upload any data to a remote server, all testing is done locally. Many validators will behind the scene upload the markup to online services such as W3C. HTML-validate performs all validation locally, no markup leaves your machine, providing a faster and more secure response which can easily be integrated with tools and IDEs.
• Strict parsing:
  • When rendering a document it is useful to try to correct malformed markup but a validator should be strict. No corrections, assumptions or guessing is done. If the markup is invalid the parser will tell you so.
  • By ensuring the markup is strictly valid it reduces the amount of bugs where different browsers autocorrect the markup differently (this is especially true for mobile browsers).

Website: gitlab.com/html-validate/html-validate
Support:
Developer: David Sveningsson
License: MIT License

HTML-validate is written TypeScript. Learn TypeScript with our recommended free books and free tutorials.

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