EPUB Checker
Check an EPUB for the errors that make stores reject it: mimetype, metadata, manifest, spine, navigation and broken links.
Free, no uploads, no sign-up. Runs 100% in your browser.
How EPUB Checker works
The book is unzipped in your browser and checked step by step: the mimetype entry, container.xml, the OPF package (title, language, identifier, modified date), every manifest file, the spine, the nav or NCX, and each XHTML file for broken markup and links.
Input: EPUB. Output: CSV.
How to use EPUB Checker
- Drop an EPUB.
- Read errors first, then warnings.
- Fix them and check again, or download the report.
Tips
- Nothing is uploaded. Your files stay in this browser tab.
EPUB Checker FAQ
- Are my files uploaded?
- No. This tool runs entirely in your browser tab. Files are read from your disk into memory and the result is generated locally.
- Is it free? Are there limits or watermarks?
- Free and open source (MIT). There are no file-size caps, daily quotas, accounts or watermarks.
- Does it work offline?
- Yes, once the page (and any engine it needs) has loaded, it keeps working without a connection thanks to the service worker cache.
Related tools
- EPUB Editor: Change the cover, title, author, series and tags of an EPUB, shrink its images, or merge several books.
- E-book Converter: Convert EPUB, MOBI, AZW3, FB2, CBZ, DOCX, PDF, TXT and more to EPUB, PDF, Word, HTML, TXT, Markdown or FB2.
- E-book Reader: Read EPUB, MOBI, AZW3, FB2 and CBZ comics in your browser with themes, search and a table of contents.
- Kindle Highlights Exporter: Turn My Clippings.txt into clean Markdown, CSV or JSON, sorted by book, with duplicates merged.