01
Drop an EPUB
Up to 90 MB. Nothing is uploaded to open it.
EPUB checker and validator, with built-in repair.
Open an EPUB to repair common markup and navigation issues locally, then review remaining findings in the editor. Choose a server check to validate your exported draft with EPUBCheck and Ace.
- Broken markup, navigation and roles repaired as it opens
- Findings you can act on, not just a list
- Repair runs in your browser, with no account
- 3 checks with a verified free account — EPUBCheck and Ace
How it works
02
See what was repaired
Counts by category, then what changed in each chapter.
03
Fix the rest and check it
Edit here, then upload the exported draft for EPUBCheck and Ace. A verified free account includes 3 checks total.
What is corrected, and what is only reported.
Repaired for you
Invalid markup, missing namespaces, illegal URLs and unusable ARIA roles are corrected while the book opens.
Navigation rebuilt
A missing or unreadable table of contents is recovered from the book's own files.
Implied accessibility roles restored
Roles the semantics already imply are added, so assistive technology is told what the book means.
Official checks
EPUBCheck and Ace by DAISY run against the exported file and report with their own versions.
Don't have an EPUB yet?
Convert your existing documents first — then check the result here.
Learn about EPUB validation
How a broken EPUB is repaired on open
E-BOOKA repairs the file while it loads. Invalid markup is corrected. Missing navigation is rebuilt from the spine and the chapter files. Accessibility roles no reading system recognises are removed, and roles implied by epub:type are added where the file left them out.
This runs in your browser. Nothing is uploaded and no account is needed. The editor then lists what changed, by category and by chapter. Use the EPUB editor to review your chapters, metadata, and cover before exporting.
For example, a missing table of contents can be rebuilt. Missing image descriptions still need your judgment: review and add useful alternative text before checking again.
What EPUB validation checks, tool by tool
Five checks run on a book here. They test different things, so passing one says nothing about the others.
Repair runs first, in the browser, as the file loads. It corrects invalid markup, rebuilds missing navigation and fixes accessibility roles.
Pre-publish checks also run in the browser and re-run as you edit. Sixteen rules cover metadata, structure, table of contents, images, links and accessibility: a missing author, a heading that jumps from H1 to H3, a link to a file the book does not contain, an image without alternative text. Each one can be fixed in the editor.
EPUBCheck checks conformance with the EPUB standard. Fix reported errors and review your chosen store’s requirements before submitting.
Ace by DAISY checks accessibility: alternative text, ARIA roles, document semantics and reading-order metadata. Automated results still require manual accessibility review.
Amazon KDP and Apple Books readiness interprets the two reports against store-specific guidance and comes with Publisher. Checks do not guarantee store acceptance.
EPUBCheck and Ace upload and check the file the editor would export, after repairs and edits—not an untouched assessment of your original file. A verified free account includes 3 checks total. Library adds 25 checks a month; Publisher includes unlimited checks.
Repair and the pre-publish checks need no account at all.
What EPUB validation cannot decide
Automated checks find what is missing, not what is wrong.
A checker reports that an image has no alt attribute. It cannot judge whether alt="image1" describes the image. It reports that a heading jumps from H1 to H3. It cannot tell whether that H3 belongs to the section above it.
Reading order, the usefulness of alternative text, and colour contrast in your own stylesheet need a person. Ace says as much in its own output: automated testing does not replace manual accessibility review.
Those are listed as manual steps rather than counted as passes.