Free CBZ to EPUB Converter: No Sign-up, Files Never Uploaded
This free CBZ to EPUB converter runs entirely on your device. You do not need an account or a login, and your files are never uploaded, so they never leave your browser.
The book is unpacked into chapters, text and images, rebuilt, and packed again as EPUB.
This pair runs on code that is already in the page, so there is no extra engine to download. Each page image becomes one page.
- Free
- No sign-up
- Never uploaded
- No watermark
Your files are converted on your device and never uploaded.
How to convert
- Add your CBZ files by dragging them onto the converter or by using the file picker.
- Check that EPUB is the selected target format; it is already chosen on this page.
- Open the options if you want to change the settings shown for the target, or keep the defaults.
- Press Convert and watch the progress shown for each file.
- Download each result, or take them all together as one ZIP when you converted several files.
Features
- Reads .cbz and writes .epub.
- Free, with no watermark added to the result.
- No sign-up and no login.
- Your files are never uploaded and never leave your device.
- Batch conversion with a ZIP download for several results.
- The input is recognised by its content, not only by its file name.
Supported formats
| Format | Read | Write | Notes |
|---|---|---|---|
| Comic book (CBZ).cbz | Yes | Yes | A ZIP archive of page images, read by comic book apps. |
| EPUB.epub | Yes | Yes | The open standard for e-books; text reflows to fit any screen size. |
About the formats
About CBZ
A ZIP archive of page images, read by comic book apps.
Pages are plain images, so no text can be reflowed.
About EPUB
The open standard for e-books; text reflows to fit any screen size.
A ZIP of HTML files, maintained by the W3C (formerly the IDPF).
Read by almost every e-reader app, and by Kindle through Send to Kindle.
CBZ vs EPUB
CBZ does not support transparency, and EPUB does not.
Comic book (CBZ) files use the .cbz extension and EPUB files use .epub, so the converted file gets a new name with the new extension.
Privacy: how it works
- Your CBZ files stay on your device. The page reads each file with the browser's file API, converts it with code running in the tab, and hands the result back as a download. No upload happens, so there is no copy of your file on our servers to protect, delete or leak.
- There is nothing to sign up for and no login. The converter does not ask for an email address, and it does not need to know who you are to do its job.
- You can check the claim yourself: open your browser developer tools, watch the Network tab while a file converts, and you will see no request that carries your file.
Tips
- Check chapter breaks and images in the result before you copy it to your reader.
- DRM-protected books cannot be converted, so use files you own without protection.
- Pick the format your reader supports natively; EPUB is the safest choice for most apps.
- Keep the original file in case a cover or a table looks different after conversion.
- This page converts one way only; EPUB files cannot be turned back into CBZ here.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial, no credit card and no watermark added to your results. Ulkaa Tool does the conversion with your own device, so there is no server bill to pass on to you.
Are my files uploaded?
No. Your CBZ files are read and converted inside your browser and are never sent to Ulkaa or to anyone else. The result is created on your device and you save it from there.
Do I need an account?
No. There is no sign-up and no login. Open the page, add your files and convert. An Ulkaa account is not needed for anything on this tool.
Is there a file size limit?
No limit is set by us. The real limit is your device: the conversion uses your own memory and processor, so very large files can be slow, and a very big batch may need to be split into smaller runs.
What is the difference between CBZ and EPUB?
CBZ does not support transparency, and EPUB does not. Comic book (CBZ) files use the .cbz extension and EPUB files use .epub, so the converted file gets a new name with the new extension.
Can I convert many CBZ files at once?
Yes. Add as many files as your device can handle. Each one is converted on its own and you can download them one by one or as a single ZIP.
Will anything be lost when I convert CBZ to EPUB?
The converter keeps the content of the file. Check the result once, since small differences in metadata or colour handling can happen between formats.
Can I convert EPUB back to CBZ?
Not on this page. This conversion goes one way. Open the EPUB page to see which formats it can be converted to.