[GUI Plugin] Extract E-ISBN

[Shiesty_Apps]

This plugin is an unofficial fork of Extract ISBN, originally developed by kiwidude.

Extract E-ISBN was created for ebooks whose copyright pages list several edition-specific ISBNs, such as hardcover, paperback, and ebook ISBNs. The original plugin generally returns the first valid ISBN it finds, which may be the hardcover ISBN. This fork looks for edition labels associated with each ISBN and gives priority to the ISBN identified as belonging to the electronic edition.

Main Features:

• Prefers a valid ISBN associated with labels such as eBook, e-book, e book, EPUB, electronic, or digital.
• Supports edition labels placed before the ISBN or immediately afterward in parentheses or brackets.
• Recognizes print-edition labels such as hardcover, hardback, paperback, softcover, and print to avoid selecting the wrong ISBN.
• If no ebook-labelled ISBN is found, falls back to the original Extract ISBN behavior and returns the first valid ISBN found.
• Supports both ISBN-13 and ISBN-10. An ebook-labelled ISBN-10 will be preferred over an ISBN-13 belonging to a print edition.
• Scans available formats for the selected book or books in preferred input-format order.
• Runs as a background job in Calibre and prompts you before updating the ISBN metadata.
• Scans book content while excluding HTML markup.
• For PDF files, scans the first 10 pages and then the last 5 pages when necessary.
• For EPUB and other non-PDF formats, scans files at the beginning and end of the book before checking the remaining files.
• Restricts ISBN-13 results to configured prefixes. The defaults are 977, 978, and 979.
• Can optionally show only the books whose ISBN metadata was updated after the scan finishes.
• Uses a separate plugin name and internal namespace, so it can be installed alongside the original Extract ISBN plugin.

Examples:

Extract E-ISBN supports edition labels placed before the ISBN:

Hardcover ISBN: 9780306406157
eBook ISBN: 9781402894626

It also supports edition labels placed immediately after the ISBN:

ISBN 9780756418854 (hardcover) | ISBN 9780756418861 (ebook)

In both cases, Extract E-ISBN selects the ISBN identified as belonging to the ebook edition.

Special Notes:

• This is an unofficial fork based on Extract ISBN version 1.6.6. It is not maintained or supported by the original plugin author.
• If the publisher does not identify the electronic edition with a recognizable label, the plugin falls back to the first valid ISBN it finds.
• Labels placed after an ISBN must appear immediately afterward in parentheses or brackets. This prevents a label belonging to the next ISBN from being incorrectly associated with the previous one.
• The plugin can only use ISBN information present in the book’s text. It does not look up editions through an online metadata service.
• Because scanning can run in the background, avoid modifying, deleting, or converting the books being scanned until the job finishes.
• Requires Calibre 2.0.0 or later.
• Licensed under GPL v3. The Python source is included in the plugin ZIP.

Installation:

1. Download the attached Extract E-ISBN.zip file. Do not extract it.
2. Open Calibre and go to Preferences → Plugins.
3. Click Load plugin from file.
4. Select Extract E-ISBN.zip and accept the security warning.
5. Restart Calibre.
6. Add the Extract E-ISBN action to a toolbar or menu through Preferences → Toolbars & menus if it does not appear automatically.

Version History:

Version 1.0.0 – September 18, 2026

• Initial release of Extract E-ISBN.
• Added preference for ebook-labelled ISBNs.
• Added recognition of electronic and print-edition labels.
• Supports edition labels placed before an ISBN or immediately afterward in parentheses or brackets.
• Added a separate plugin identity so the fork can coexist with Extract ISBN.
• Preserved the original first-valid-ISBN behavior as a fallback.

Credits:

Extract E-ISBN is derived from the GPLv3-licensed Extract ISBN plugin by kiwidude. Most of the scanning, configuration, job-processing, and user-interface code comes from that project.

[Shiesty_Apps]

If you have an existing ISBN in the field, you may have to click off and click back on the book in order to visually see the ISBN update with the ebook ISBN. It does update, but I guess Calibre doesn't refresh this field in real time.

[JSWolf]

Originally Posted by Shiesty_Apps

If you have an existing ISBN in the field, you may have to click off and click back on the book in order to visually see the ISBN update with the ebook ISBN. It does update, but I guess Calibre doesn't refresh this field in real time.

Have a look at the code for Count Pages plugin. It does some sort of real time update after it's done it's counting. I don't know if the code is appropriate or not. But it can't hurt to have a look.

[Shiesty_Apps]

Originally Posted by JSWolf

Have a look at the code for Count Pages plugin. It does some sort of real time update after it's done it's counting. I don't know if the code is appropriate or not. But it can't hurt to have a look.

Sweet, I’ll take a look into that. Thanks!