HTML Checker

The HTML checker analyzes user-provided markup to verify conformance with modern HTML5 standards. It detects syntax errors, misplaced elements, missing attributes, and structural issues, returning precise reports that include the location in the source. The tool is designed for developers, educators, and QA teams who want fast, objective validation without manual code reviews. Reports can be generated in JSON or plain text, enabling easy integration with tooling and documentation. Under the hood it relies on a strict parser and a catalog of rules covering doctype correctness, tag nesting, attribute semantics, and URL/URI encoding. When a violation is found, the system categorizes severity, suggests fixes, and highlights the affected region. It also flags accessibility and semantic concerns that impact search engines and assistive technologies. The approach emphasizes reproducibility and deterministic results across environments. The solution offers concrete value for both individual developers and teams employing continuous integration. In CI, it can fail builds on critical errors, while on local machines it accelerates debugging and improves learning for students. Unique differentiators include detailed per-error guidance, line-accurate reporting, and exportable results suitable for audits and compliance reviews. Core features include syntax validation, structural checks, attribute rules, encoding verification, and exportable reports. Typical use cases include validating static HTML files, preparing templates, teaching HTML basics, and ensuring content adheres to internal standards before deployment. The tool supports batch processing, historical comparisons, and clear, actionable recommendations.