EPUB validator

Upload any EPUB and get a plain-English health check. No jargon — every problem is explained the way a helpful editor would explain it, with a suggested fix.

🔒 Your files never leave your browser. Validation happens locally on your device.

What gets checked

• File structure — is it a real EPUB readers will open?
• Table of contents — can readers tap between chapters?
• Metadata — title, author, language and unique ID present?
• Reading order — does every chapter exist and in order?
• Chapter formatting — is every page valid, readable XHTML?
• Images — is every referenced image actually included?
• Cover — is a cover image declared for stores?