Convert Documents to HTMLZ Online — Free eBook Converter
This free online HTMLZ converter lets you transform documents and eBooks from a wide range of formats into the HTMLZ format — a zipped HTML-based eBook container that is easy to read, share, and edit.
What is HTMLZ?
HTMLZ is an open eBook format that packages a standard HTML file along with its associated assets — images, stylesheets, and metadata — inside a single ZIP archive with the .htmlz extension. Because it is built on familiar web technologies, the content inside an HTMLZ file can be opened, inspected, and edited with any text editor or web browser after extracting the archive. The format is supported by popular eBook management software such as Calibre, which uses it as an intermediate format for conversions and edits.
Why convert to HTMLZ?
HTMLZ offers a practical middle ground between raw HTML and more rigid eBook formats. Common reasons to convert to HTMLZ include:
- Easy editing: Because the content is standard HTML, you can tweak text, headings, and styles without specialist eBook tools.
- Compact packaging: All resources are bundled in one ZIP file, making it simple to transfer or archive.
- Calibre compatibility: HTMLZ is a first-class format in Calibre, making it ideal as a stepping stone when converting between other eBook formats.
- Preservation of formatting: Text layout, basic styles, and embedded images are retained during conversion.
Supported input formats
The converter accepts a broad range of document and eBook input formats, including PDF, DOCX, DOC, EPUB, MOBI, FB2, RTF, TXT, LIT, LRF, PDB, OEB, AZW, and more. If your source file is a common document or eBook type, it is very likely supported — simply upload it and the tool will handle the rest.
Frequently asked questions
Is this HTMLZ converter free to use?
Yes, the converter is completely free. No subscription, account, or payment is required to convert files to HTMLZ.
What happens to my uploaded files?
Files are processed on the server solely to perform the conversion and are deleted automatically afterwards. They are not stored permanently or shared with third parties.
Which programs can open an HTMLZ file?
HTMLZ files are natively supported by Calibre, a free and open-source eBook manager. You can also extract the ZIP archive and open the HTML content directly in any web browser.
Will my images and formatting be kept after conversion?
In most cases, yes. The HTMLZ format preserves text layout, basic styles, and embedded images. Results may vary depending on the complexity of the source document.
Can I convert HTMLZ back to another format like EPUB or MOBI?
Yes. Once you have an HTMLZ file, you can use the other eBook converters on this site — or tools like Calibre — to convert it onward to EPUB, MOBI, AZW3, and many other formats.