Find out why an EPUB will not open, will not upload, or gets rejected by Send to Kindle - and fix it in one click. The checks run in your browser; for badly broken books, our server can rebuild the whole thing with Calibre. Then polish the details with the EPUB Metadata Editor.
Checked in your browser - nothing is uploaded unless you ask for a server rebuild.
Package and manifest problems, missing metadata, broken spine entries and junk files are fixed exactly. Broken XHTML pages are re-written as valid XHTML, keeping their text and markup.
Badly broken books can be rebuilt on our server with Calibre - a full re-conversion that also rebuilds the table of contents.
EPUBCheck is the official, very strict validator used by publishers. This tool focuses on the problems that actually stop a book from opening or uploading.
It is ideal before Send to Kindle, Kobo or Apple Books - see the Send to Kindle guide.
No - the checks and fixes run in your browser. Only if you click Rebuild on our server is the file sent to us, and it is deleted after a few hours.
The usual causes are a misplaced mimetype file, missing files in the manifest, broken XHTML pages or a missing language. Check the book here, fix it and send the fixed copy - see the Send to Kindle guide.
Only the problems you tick are changed. Text, images, fonts and styling stay as they are. Repaired XHTML pages keep their content but are re-written cleanly.
No. EPUBCheck is the strict official validator. This tool checks the problems that make books fail in real readers and stores, and fixes them for you.
It converts the EPUB to a fresh EPUB with Calibre, which rebuilds the package, table of contents and pages from scratch. Use it when the in-browser fixes are not enough.
No. Books with store copy protection cannot be checked or changed.