ITST Online Validator

ITST Online Validator analyzes input URLs or HTML snippets to assess syntax correctness, structural conformance, and semantic quality against recognized web standards. It is used by web developers, QA engineers, content managers, and SEO specialists who need quick, standards-based validation results without running local tooling. It supports full HTML documents, HTML snippets, and lists of URLs for batch checks; results are machine-readable and suitable for integration into pipelines.
Core Logic & Features: Required features include HTML5/CSS validation, character encoding verification, tag nesting checks, attribute usage rules, link integrity, and basic accessibility indicators. Optional/advanced features cover CSS linting, JSON-LD and schema.org validation, hreflang consistency checks, and batch validation with aggregated summaries. The tool enforces established standards (W3C, WCAG basic signals) and produces structured error items with location data and remediation hints.
Inputs & Outputs: Inputs consist of a URL or HTML snippet (required); optional validation modes (HTML, CSS, Accessibility) and a batch list. Outputs are a machine-readable report with overall status, a list of errors and warnings including location, code context, and suggested fixes, plus human-readable summaries and export options (JSON/CSV).
Algorithms & Calculations: The validator uses robust parsers for HTML5, CSS, and structured data; applies standard rule sets from official validators; computes a conformance score from the ratio of passed checks to total checks; flags deprecated or experimental constructs and highlights performance blocking issues; cross-checks external resources where available.
Error & Edge Cases: If inputs are missing or invalid, domain-level errors are returned; unreachable resources yield clear fetch errors with retry guidance; partial reports are produced when resources are blocked or cross-origin policies prevent retrieval; conflicting rules produce unambiguous remediation notes.
Industry/Region & Localization: Aligns with international web standards; supports UTF-8 by default; localized messaging and time/date formats can be enabled as needed.
Assumptions & Exclusions: Assumes access to provided URL or HTML content; does not execute user scripts or render the page; not a full browser; excludes proprietary formats not part of standard validators.