Apple Books EPUB Checker

This is a pre-flight check for self-publishing authors and small presses preparing an EPUB for Apple Books, whether you upload directly through Apple Books Connect or route the file through an aggregator like Draft2Digital. It looks specifically at the things Apple's pipeline tends to care about — a present cover, complete metadata, a navigable table of contents, EPUB 3 navigation, and a sane reading order — so you can catch the obvious blockers before you sit through an upload and a rejection.

It fits naturally into the last mile of ebook production: you have exported an EPUB from your authoring tool and want a second opinion before submission. It also helps when a previous Apple submission bounced and you are trying to narrow down which field or file was at fault. Because it reports per-check detail, it doubles as a quick metadata audit for a back catalogue you are about to re-distribute.

It is not a converter, an editor, or a store-upload tool. It does not create EPUBs, fix them, or send anything to Apple. If you need to add a cover, edit metadata, or repackage a delivery folder, those are separate tasks — this tool only inspects and reports.

The flow is one step: drop an .epub file onto the dropzone (or pick it through the file dialog), and the check runs immediately in your browser. There is no paste option and no other input format — it expects a real EPUB container. Parsing and all checks happen locally; nothing is uploaded, and closing the tab discards everything. DRM-protected files are detected and refused rather than inspected.

The report covers: presence of a cover image, title, author (dc:creator), language (dc:language), and a book identifier such as an ISBN or UUID; total file size against Apple's limits; an EPUB 3 nav.xhtml document and a table of contents (nav or NCX); a non-empty spine for reading order; and a correct mimetype entry. Each line returns pass, warning, or fail with a short explanation, and you can download the whole thing as a plain-text readiness report.

Two honest notes on scope. The cover check confirms the image exists and flags one that is suspiciously small by file size, but it reads byte size, not actual pixel dimensions — so it cannot confirm the 1400 × 1873 px minimum on its own. The accessibility coverage here is light (navigation and language basics), not a full EPUB Accessibility 1.1 or WCAG audit.

The biggest pitfall is reading "Ready for Apple Books Connect" as a guarantee. This is an unofficial pre-check; Apple's own ingestion and review can still flag issues this tool never sees, including content-policy, fixed-layout, and rich-media specifics. Treat a clean result as "no obvious blockers found," not "approved."

Watch the cover check in particular. A pass means a cover file is present and not tiny, but a low-resolution image that is still over the size threshold can pass here and be rejected by Apple for failing the pixel minimum. Verify the actual dimensions yourself. Similarly, a present identifier passes even if the ISBN is wrong or already assigned to another edition — the tool checks that the field exists, not that the value is valid.

Other common misses: warnings (missing identifier, NCX-only navigation, a large file) are easy to skip past, but Apple often prefers EPUB 3 navigation and a proper ISBN, so a warning is worth acting on. And if you feed it a non-EPUB file or a corrupted container, parsing fails outright rather than producing a partial report.

Start with the failures, since those are the items most likely to stop an upload: a missing cover, empty title or author, absent language tag, missing table of contents, a bad mimetype, or an empty spine. Then resolve the warnings — add an ISBN or unique identifier, move to EPUB 3 nav.xhtml if you are on NCX only, and reconsider an unusually large file. Re-run the check after any edit, since the tool only reflects the file you dropped in.

Confirm the things the tool cannot fully verify: open the cover and check it meets Apple's pixel minimum (1400 × 1873 px, with 2000 × 2667 px or larger recommended), and read back the title, author, language, and identifier values to make sure they are correct and not just present. Skim the actual reading order in a real reader, because a non-empty spine does not prove the chapters are in the right sequence.

For any official, contractual, or revenue-bearing release, treat this as a first pass only and validate with Apple's own transporter and Apple Books Connect, plus a dedicated accessibility tool such as Ace by DAISY if accessibility compliance matters. A clean report here reduces surprises; it does not replace Apple's verification.