About Tanko
Tanko turns CBZ, CBR and PDF comics and manga into EPUB files that read properly on a Kindle or Kobo. It is free, it needs no account, and the files you convert never leave your device.
Why it exists
E-readers are good at novels and awkward with comics. A CBZ dropped onto a Kindle often arrives with pages in the wrong order, double-page spreads squeezed onto one screen, and manga that turns the wrong way. Desktop tools fix this, but they need an install, and most online converters ask you to upload a whole volume to a server you know nothing about.
Tanko was built to do the conversion in the browser tab instead. You drop a file, pick the device you read on, and download an EPUB sized for that screen.
How it works
The archive is unpacked in your browser with JSZip for CBZ and a WebAssembly build of unrar for CBR. PDF pages are rendered with PDF.js. Each page is then resized and adjusted for the screen of the device profile you chose, wide spreads are split into single pages when that reads better, and the reading direction is written into the book so right-to-left manga turns the right way.
All of that runs in a background worker on your own machine. Tanko has no upload endpoint, so there is nothing on a server to delete afterwards. The practical limit is your device memory: very large volumes convert more slowly on a phone than on a laptop.
What it does not do
Tanko works with files you already own. It does not download, host or index books, and it does not remove DRM. Files bought from a store with copy protection will not open.
Who makes it
Tanko is made by Nathan Stewart at I4C Studio, a one-person product studio that builds developer tools and small, single-purpose web tools. The same person writes the code, the guides on this site and the replies to your email.
The studio's other free browser tools work the same way, on your device with no upload:
How it is paid for
Tanko is free to use, with no account, no trial and no paid tier. Advertising through Google AdSense covers the hosting. The ads are the only part of the site that involves a third party beyond hosting and aggregate analytics, and the privacy page explains exactly what that means.
Where to start
Found a file that will not convert, or a mistake in a guide? The contact page says how to report it.