HTMLZ Converter
Convert files to and from HTMLZ online for free. Fast, secure, and high-quality file conversion with no sign-up or software required.
Maximum file size is 1GB
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Drag and drop, click to browse, or paste a URL. Batches take up to 20 files at once - 230+ input formats across video, audio, image, document, and archive types.
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What is an HTMLZ file?
HTMLZ is a zipped container format created primarily for the Calibre eBook management software to package HTML content into a portable eBook structure. It comprises a ZIP archive holding an index.html file, a style.css stylesheet, image assets, and a metadata.opf file following the Open Packaging Format standard. Unlike EPUB, HTMLZ does not enforce the strict containment structure of the IDPF specifications, serving instead as a lightweight wrapper for HTML-based text.
How to open an HTMLZ file
HTMLZ files are natively processed by the Calibre e-book management suite, which can view or convert them to standard formats like EPUB or MOBI. Because the underlying structure is a ZIP archive, users can also rename the file extension to .zip and extract the HTML and CSS components using standard compression utilities like 7-Zip or WinRAR for manual viewing in a web browser.
HTMLZ Technical Info
- Full Name
- Zipped HTML eBook
- Developed By
- Kovid Goyal (Calibre)
- Initial Release
- 2010s
- MIME Type
- application/zip
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