EPUB Validator

The EPUB Validator analyzes EPUB 2 and EPUB 3 files to verify structural conformance, metadata integrity, packaging, and accessibility readiness. It accepts EPUB uploads or a URL to an EPUB resource, runs a comprehensive set of checks, and returns a detailed report that highlights errors, warnings, and suggested fixes for editors and QA teams.
Conceptually, the tool parses the ZIP container, inspects the mimetype and container.xml, analyzes the OPF package, manifest items, spine ordering, and resource references, and applies EPUB 2/3 rules. It also runs accessibility checks aligned with WCAG guidelines and provides both a machine-readable JSON report and a human-friendly summary of issues.
Primary users include authors, editors, QA engineers, librarians, and digital publishers who require repeatable quality checks, reproducible results, and CI-friendly integration. The tool differentiates itself by combining strict structural validation with metadata cross-field validation, automated accessibility checks, and exportable reports that support remediation workflows and store submission readiness.
Use cases cover pre-submission validation for ebook stores, batch validation in production pipelines, and integration with build systems for continuous quality assurance. Outputs enumerate exact errors with locations, affected files, and remediation guidance, while summarized reports facilitate executive oversight.