EPUB Reader & Inspector

about this tool

An EPUB is a ZIP with rules

Underneath, an EPUB is an ordinary ZIP archive holding XHTML, CSS and images, plus three things that make it a book: a mimetype file, a META-INF/container.xml saying where the package document is, and that package document listing every file, the order to read them in, and the metadata.

This tool follows that chain — the same ZIP directory reader the archive tool uses opens the file, then the container points at the package, and the package gives the manifest, the spine and the title. The table of contents is read from an EPUB 3 navigation document or an EPUB 2 NCX, whichever the book has, and the nesting is kept.

Reading it

The chapter list is the spine, which is the order the book is meant to be read in, labelled from the table of contents where the two agree. Each chapter is shown as text with its headings and paragraphs kept as spacing.

The markup is deliberately not rendered. An EPUB is arbitrary XHTML from a file you were handed, and rendering it means running its markup and styles inside this page. Taking the text out instead means a book can be read and its words saved without that risk. Scripts and styles are dropped, and whitespace inside a paragraph is collapsed the way a browser would.

Each chapter shows its word count and roughly how long it takes to read, at a middling two hundred and twenty words a minute. A chapter or the whole book can be saved as plain text.

What it checks

Three things are fatal, because without them there is no book: a missing container, a missing package document, and a package the container points at that is not in the archive. Everything else is reported and the book opens anyway.

The two worth knowing about are ordering rules most people never see. The mimetype file must be the first entry in the archive and stored uncompressed, so that a reader can identify an EPUB from its first bytes without unpacking anything. Books get this wrong often and most readers forgive it, so the tool says so rather than refusing. A book carrying META-INF/encryption.xml has DRM or obfuscated fonts, and those parts will not open here or anywhere without the keys.

Limits

No rendering, so no images inside the text, no fonts and no layout — the cover is shown on its own. No DRM, ever. No writing: this reads a book, it does not edit or repack one; the archive tool will do that. Very large books are held in memory whole. Nothing is stored between visits.

An EPUB is a zip archive underneath, so zip inspector will show you its internal structure. For the same job on the other common book format, PDF to text extracts prose from a PDF, and the saved text opens in the Markdown editor.

questions

Why is the formatting gone?

On purpose. An EPUB is arbitrary XHTML and CSS from a file someone gave you, and rendering it would mean running that markup in this page. The text is taken out instead, with headings and paragraphs kept as spacing. It is for reading and for getting the words out, not for typesetting.

It says my book has problems but opens it anyway.

The specification asks that the mimetype file be the very first entry in the archive and stored uncompressed, so that a reader can identify the format from the first bytes. Plenty of books get that wrong and most readers cope, so it is reported rather than refused. A missing container or package document is fatal, because then there is nothing to read.

Can it open a book from a shop?

Only if it has no DRM. A book with DRM carries an encryption file, which the tool spots and tells you about; the encrypted parts cannot be read here or anywhere else without the shop’s keys.

What is the difference between the contents list and the reading order?

The spine is the order the files are meant to be read in, and the table of contents is the navigation the author wrote, which may skip files or point into the middle of them. The list here shows the spine, labelled from the table of contents where the two line up.

Is my book uploaded?

No. It is unpacked and read in this page. Nothing leaves your device and nothing is stored between visits.