I built a browser-based CBZ to PDF converter that keeps comics private

Recently, I wanted to convert some CBZ comic files into PDF.

The usual solution was simple:

Upload the file → wait → download the PDF.

But there was one problem.

Comic archives can easily become hundreds of megabytes, and uploading a personal comic collection to an unknown server didn't feel like the right solution.

So I built Mangavia.

What is CBZ?

CBZ is a popular comic book archive format.

Technically, a CBZ file is a ZIP archive containing comic page images.

Example:

comic.cbz
├── 001.jpg
├── 002.jpg
├── 003.jpg
└── ...

Because CBZ files are basically image collections, they can be processed directly in the browser.

Processing comics locally

Mangavia converts CBZ files completely inside your browser.

The process:

1. Read the CBZ archive
2. Extract comic pages
3. Sort images in the correct order
4. Generate a PDF
5. Create the download file

Your comic files never leave your device.

Why browser-based?

For this type of tool, a server is not always necessary.

Local processing provides:

• Better privacy
• No upload waiting time
• No storage limitations
• A simpler user experience

Modern browsers are surprisingly powerful.

Challenges

The hardest parts were not only generating the PDF.

The challenging areas were:

• Handling large CBZ archives
• Keeping page order correct
• Supporting different image formats
• Managing browser memory usage

What's next?

The current version focuses on simple CBZ to PDF conversion.

Future improvements include:

• Batch conversion
• Better comic collection workflows
• More reading-friendly options

Try Mangavia

https://cbztopdf.com

I would love to hear feedback from comic readers and developers.