Show the Working

HTMLZ to HTML

Nothing you choose here leaves your browser, and nothing is downloaded to make it work. Your browser already gzips and unzips; this page is the rest.

…or drop one anywhere on this page.

One page out of Calibre's archive, pictures included.

An .htmlz is Calibre's: a ZIP holding an index.html and whatever it refers to. This takes the document out and writes the pictures into it as data URIs, so what you get is a single file that works anywhere with nothing beside it. The title and author come from the metadata.opf if the archive has one.

HTMLZ is Calibre's, and nothing else defines it

There is no published specification. An .htmlz is what Calibre writes: a ZIP with an index.html at its root, the pictures and stylesheets it refers to beside it, and usually a metadata.opf carrying the title and author. That is the whole of it.

So the only rule that matters is the name of that file. If an archive has no index.html but exactly one HTML file, this takes that one and says which it took. If it has several and no index, it refuses rather than guessing — picking the alphabetically first would be a coin toss with your book.

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