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EPUB Validator Pro

Deep EPUB validation — ghost spacing detection, duplicate ID scan, OPF manifest check, cover dimensions, and store-specific pass/fail report for KDP, Apple Books, and Google Play.

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EPUB Validator Pro for KDP and Apple Books

The free EPUB validator catches basic structure errors. This tool goes deeper — ghost spacing, duplicate IDs, OPF manifest issues, and cover dimension problems that cause rejections on KDP, Apple Books, and Google Play.

What It Checks

Ghost spacing that breaks reflowable text. Duplicate ID errors that cause navigation failures. OPF manifest completeness. Cover image dimensions against store requirements. Store-specific pass/fail report for KDP, Apple Books, and Google Play so you know exactly where your file will be accepted.

Who This Is For

Authors who have had an EPUB rejected by a store without a clear reason. Formatters delivering files to clients who publish across multiple platforms. Anyone uploading to Apple Books or Google Play where validation requirements are stricter than KDP.

How to Use It

Upload your EPUB file and get a detailed report with pass/fail status for each store and specific fixes for every issue found.

For the full accessibility requirements — alt text on images, language declaration, heading structure, and epub:type annotations — see accessible EPUB.

Common questions

The free validator checks structural integrity — mimetype, container, OPF, metadata, spine, navigation, cover reference, and file size. The Pro scan goes deeper: ghost spacing, duplicate ID errors, OPF manifest completeness, cover image dimensions against store requirements, and a store-by-store pass/fail breakdown for KDP, Apple Books, and Google Play.
3 AI credits per validation.
Possibly. The free validator confirms your file is structurally readable. It won't catch ghost spacing, duplicate IDs, or a cover image that's the wrong dimensions for a specific store. If you're submitting to Apple Books, Google Play, or IngramSpark — all stricter than KDP — the Pro scan is worth running before uploading.
Ghost spacing is leftover empty paragraph tags or non-breaking space characters carried over from a Word or Google Docs export. They're invisible in most previews but cause inconsistent gaps between paragraphs on actual eReaders. Apple Books flags these during review; KDP is more forgiving but the reading experience suffers.
It gives a separate pass/fail result for KDP, Apple Books, and Google Play, showing which issues would cause a rejection on each store specifically. The same file can pass KDP and fail Apple Books — the report tells you exactly where and why.
It reports issues with specific locations and descriptions so you know exactly what to fix and where. Fixing deep structural issues like duplicate IDs or ghost spacing requires editing the underlying EPUB source files — use the report to guide those edits in Sigil or your EPUB editor.
Run the free validator first. If it finds structural errors, fix those before running the Pro scan — the Pro scan's deeper checks are only meaningful once the basic structure is sound.