EPUB Checker
Validate your EPUB files for structure, metadata, and best practices — instantly, for free.
Free toolDrag and drop your .epub file here
or
Browse filesYour file is processed securely and deleted immediately after analysis.
Structure Validation
Checks ZIP integrity, mimetype, container.xml, OPF package document, manifest, and spine reading order.
Content Validation
Validates XHTML well-formedness, UTF-8 encoding, internal references, and duplicate ID detection across content documents.
Best Practice Analysis
Reviews file sizes, image optimization, naming conventions, and cover image declarations.
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Validation based on the EPUB specification maintained by the W3C and the DAISY Consortium.