You have a file that ends in .opub. It most likely came from a BOOX Picco, and the reading apps already on your computer will not open it. This guide explains what that file is, how it differs from EPUB, and how to read it or turn it into an EPUB. The reader and the converter both run in your browser. The file is not uploaded.
What an OPUB file is
OPUB is the ebook file a BOOX Picco uses. If you copied a book off the device, or someone sent you a file such as book.opub, that file is an OPUB.
For reading, it is a whole book: it has body text, a reading order, and a table of contents. It is a different file from EPUB. Renaming .opub to .epub does not make Kindle, Kobo, Apple Books, or other EPUB apps open it.
People usually need the file in one of two situations:
- The book is on a Picco, and they want it on a phone, a computer, or another e-reader.
- The
.opubis already on the computer, and nothing there recognizes it.
How OPUB differs from EPUB
EPUB (Electronic Publication) is the ebook format used by Apple Books, Google Play Books, Kobo, and most reading apps. Newer Kindle devices open EPUB as well. It is the file you can move between those apps.
OPUB is the Picco's own book file. Those other apps do not open it while it is still an OPUB.
| OPUB | EPUB | |
|---|---|---|
| Where you get it | A BOOX Picco book file | The usual ebook format |
| Extension | .opub | .epub |
| Opens in Kindle, Kobo, Apple Books | No | Yes |
| Renaming the file | Still an OPUB | Already an EPUB |
| On this site | Read it, or convert it to EPUB | Read and edit it like any EPUB |
Read the OPUB when you only need this copy on the device you are using. Convert it when the book has to open in another app.
Read an OPUB in the browser
The OPUB reader opens the file on the device you are using. Parsing happens in the browser. The file is not uploaded. The reader does not charge credits, the same as the other readers.
- Open the OPUB reader.
- Choose the
.opubfile, or drop it on the page. - Read. Chapters follow the table of contents in the file.
Text and chapters stay on your device, together with grayscale images the reader can decode. The original stylesheet is not applied, so fonts, margins, and colors will differ from the Picco screen. You are reading the book, rather than a copy of the device layout.
An OPUB larger than 32 MB is not opened. A file that is cut off, or that is not an OPUB, is turned away instead of shown as an empty book.
Convert an OPUB to EPUB
Use the OPUB to EPUB converter when you want a file other readers can open. Conversion runs in the browser, and the file is not uploaded. Sign in is required, and it costs 2 credits, the same as the other converters.
- Open the OPUB to EPUB converter.
- Choose the
.opubfile. - Download the
.epub.
The download is a standard EPUB. Check it in the EPUB reader, or copy it to Apple Books, Kobo, a newer Kindle, or another app that reads EPUB. Your original .opub stays where it was. The same 32 MB limit applies.
What is kept, and what is not
The reader and the converter keep the parts you need in order to follow the book. They do not rebuild the Picco layout, and they do not send a file back to the device.
Kept
- Reading order. The text stays in the order it is meant to be read.
- Table of contents. Chapters follow the contents list in the file.
- Body text. The words of the book are kept.
- Decodable images. Grayscale images the tool can decode are included. The first image is the cover. The rest go in an images section after the text.
Not supported
- Original CSS. Styles from the OPUB are not restored. Chapter titles come from the table of contents. Other text is paragraphs. Fonts, margins, and colors from the Picco do not come across.
- Images in the flow of the text. Pictures are not placed back between paragraphs. After the cover, further images are gathered in the images section.
- Writing the file back to a Picco. The download is an EPUB for other readers. This site does not copy a file onto a Picco or any other device.
If an image cannot be decoded, it is left out. The text is still kept.
Questions
Is the file uploaded? Reading and conversion both run in your browser. The OPUB stays on your device and is not uploaded. The reader does not charge credits. The converter requires you to sign in and costs 2 credits, the same as the other converters.
Is an OPUB an EPUB with another extension? Renaming the file does not produce an EPUB other apps can open. Use the converter when you need a real EPUB.
Will the EPUB match the Picco page? Reading order, the table of contents, and the body text are kept. Original CSS is not restored, and images are not put back in the middle of the text.
Can I send the result back to the Picco? The tool does not write a file to a Picco. You get an EPUB for other readers.
Does it cost anything? The OPUB reader does not charge credits. The OPUB to EPUB converter costs 2 credits, the same as the other converters, and you need to sign in. The file is still processed in the browser and is not uploaded.
Open or convert your file
- OPUB reader — read the file in your browser. It is not uploaded.
- OPUB to EPUB — download an EPUB that keeps reading order, the table of contents, body text, and decodable images.