Compress CBZ comics in your browser
A CBZ is heavy because every page is a picture. The pages are re-encoded at the quality you choose; ComicInfo.xml and the reading order stay put.
or browse your device. Everything is processed on this device
No CBZ to hand?
How to compress a CBZ
It is read here in the tab and goes no further. Nothing about your library reaches a server.
72% at 1600px is more than most comic readers resolve, and typically halves a photographic scan.
It reports how many pages it recompressed. Junk files removed are listed by name.
It is a valid .cbz. Sideload it into any comic reader that accepted the original.
What is actually inside a .cbz
A .cbz is a ZIP archive renamed so comic readers pick it up. Inside: a sequence of JPEG or PNG page images, often with a ComicInfo.xml that names the series, issue and page count. Rename a copy to .zip and open it and every page is sitting there as a picture, because that is exactly what it is.
Which tells you where the bytes are. There is almost no text. A 120 page comic is 120 photographs, and those are what a reader has to download, store and page through. If the file is 200MB, it is not metadata. It is the pages.
So this tool goes after the images, re-encodes each JPEG or PNG at a quality and longest edge you choose, and rebuilds the archive around them. ComicInfo.xml, folder structure and page filenames are carried through unchanged, so CDisplayEx, Perfect Viewer, YACReader and the rest still open it.
EMF, WMF, SVG and TIFF pages are left alone and named in the result, because there is nothing honest a browser can re-encode them as without changing the format the reader expects.
CBZ compression FAQ
What is a CBZ file?
A comic book archive: a ZIP of page images, usually JPEG or PNG, often with a ComicInfo.xml describing the issue. Comic readers recognise the .cbz extension and show the pages in filename order.
Will my comic still open after this?
Yes. Page filenames, folder structure and ComicInfo.xml are copied across unchanged. Readers that opened the original will open the result, because nothing about the container shape changed beyond the pixels inside each page.
Does it convert CBZ to CBR or PDF?
No. CBR is RAR, which is a different container, and PDF is a different document model. This page hands you back the same comic, smaller. If you need a different format, that is a conversion job rather than compression.
What about ComicInfo.xml?
It is kept. Series title, issue number, page count and the rest stay exactly as they were. The junk toggle only drops filesystem litter such as __MACOSX and Thumbs.db.
Why did my comic barely shrink?
Usually because the pages were already saved at a modest JPEG quality, or because they are tiny PNG panels that re-encoding cannot beat. The result panel says how many images were touched and how many were left alone.
Can it compress a CBR?
Not yet. CBR is a RAR archive, and reading RAR needs a codec this page does not ship. Rename will not help: the bytes are not a ZIP. Drop a CBR and it is packed as a ZIP until a RAR reader lands.
Is my comic uploaded anywhere?
No. There is no upload endpoint in the code. The archive is read and rebuilt in this tab, on your machine, and what you download is written straight out of memory.
Related
Same format joins the queue. Anything else re-routes to its own tool.