HTMLZ to GZ Converter
Processing entirely on your device — large files may take a moment.
Zipped HTML Ebook and Gzip Compressed File exist for different jobs: HTMLZ is Calibre's zipped-HTML ebook format: the web page plus its images in one portable archive — a "web-to-ebook" snapshot. Unpack a .gz into a normal file or repack it as ZIP/TAR when the receiving tool does not understand gzip.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How to convert HTMLZ to GZ
- 1
Select your files
Select your HTMLZ file.
- 2
Convert instantly
The file bytes are gzip-compressed in place — the same archive your server or build tool produces, made locally.
- 3
Download results
Download the .gz file — ready to upload, serve or attach.
About the HTMLZ format
HTMLZ is Calibre's answer to "save the whole page": the HTML document, its images and its stylesheet zipped into one file. It is a web snapshot that e-reader pipelines can treat as a book — a format born from the era of clipping articles for offline reading.
The archive opens in the browser, the main HTML feeds the chapter pipeline, and text or EPUB comes out with images dropped or embedded depending on the target.
+Strengths
- ✓Complete page snapshot in one file
- ✓Calibre-native round-trip
- ✓Easy to inspect (it is just a zip)
!Limitations
- −No reader displays it directly
- −Styles rarely survive conversion
- −Multi-file URLs can break image paths
About the GZ format
A .gz file is one file squeezed by gzip — not an archive. kernel.org tarballs are “tar inside gz”, but plenty of logs, JSON dumps and CSV exports travel as plain .gz. Opening one means decompressing it back to the original bytes.
Repacking into ZIP or TAR gives the decompressed file a container that every GUI tool opens without a second thought.
+Strengths
- ✓Everywhere on Linux and macOS
- ✓Fast, well-understood compression
- ✓Streams natively from any tool
!Limitations
- −Single file only — no directory tree
- −No encryption or integrity metadata
Why convert HTMLZ to GZ?
Think of it as moving your file to the container that fits the job. No reader displays it directly GZ works differently: Everywhere on Linux and macOS If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this HTMLZ to GZ converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for HTMLZ to GZ?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
What about folders and directory structure?
The full directory tree is preserved: folders stay folders, and deep paths arrive exactly as they were packed in the HTMLZ file.
Are the files inside my HTMLZ archive modified?
No. Contents are unpacked in memory and repacked into GZ byte-for-byte — the conversion changes the container, never the files inside it.