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EPUB checker

Drop in an .epub and see what a store would reject, with a plain fix for each problem. It runs in your browser, and the file never leaves your device.

Check your EPUB

Choose it or drop it here. It is checked on your device and never uploaded.

What it checks

Errors come first, then warnings, then notes for particular stores. It looks at:

  • The mimetype entry: present, first in the archive, and not compressed
  • The package's title, language, identifier, and last-modified date
  • The manifest against the files actually in the book, and the reading order
  • Every link, image, and stylesheet reference, down to the #fragment
  • A table of contents, and a cover image marked as one
  • Image formats, sizes, and types that do not match their files
  • Embedded fonts that are not really fonts
  • XHTML that a web browser forgives and an e-reader will not

What it does not check

This is a quick first pass, not a replacement for EPUBCheck. The W3C's validator tests the whole specification, including the schemas, accessibility metadata, and CSS, and it is what Apple Books and Kobo run on every upload. A book that passes here can still fail there. Run EPUBCheck before you publish.

Where the store notes come from

Each figure was checked on September 26, 2026, against the store's own help:

Tabularia, the writing app this site is for, exports EPUB 3 files that pass EPUBCheck.

Try it on your own manuscript

Nothing is metered: as many projects as you like at any length, the outline and minimap to move through them, drafts and markup mode for revising, snapshots to return to, sheets and timelines beside the page, and export to DOCX, PDF, EPUB, HTML, Markdown, plain text and Fountain. Bring in what you have already written and read it back as a book.

Start writing Subscribe to the Cloud plan See pricing

The Cloud plan is $18 a month, or $172.80 a year, and adds backup, sync across your devices, sharing a manuscript for review, and publishing your work as a web page — the readers and collaborators you invite do not need a paid account of their own. Tabularia is in Public Beta and shipping steadily; the release notes record what has landed.