The Open Publication Distribution System (OPDS) is an application of the Atom Syndication Format intended to enable content creators and distributors to distribute digital books via a simple catalog format. This format is designed to work interchangeably across multiple desktop and device software programs.
The idea of this system is to provide a format that can be used by eBook readers or even a dedicated eBook reader devices with Internet access to be able to search, discover, and download eBooks from online eBook catalogs. The system requires an RSS style processor that works with the distribution system to display choices with descriptions for the user to download. It could also provide the ability to purchase eBooks or other files. Supporting this format would be sufficient for wireless capable devices that did not include a Web Browser or that wanted to standardize the user interface experience from multiple sites.
 Online OPDS Catalogs
 (Mainly) English
All Romance eBooks: http://allromanceebooks.com/epub-feed.xml(dead as of December 31, 2016)
- arXiv: http://arxiv.maplepop.com/catalog/
- Baen eBooks (formerly Webscriptions.net): http://www.baenebooks.com/stanza.aspx
BooksOnBoard: http://www.booksonboard.com/xml/catalog.atom(dead as of April 6, 2013)
- ePubBud Children's books: http://www.epubbud.com/feeds/catalog.atom
- Feedbooks: http://www.feedbooks.com/catalog.atom
- GitBook: https://www.gitbook.com/api/opds/catalog.atom
- Internet Archive: http://bookserver.archive.org/catalog/
- ManyBooks: http://www.manybooks.net/opds/index.php
- Ludwig von Mises Institute (Libertarian think tank): http://mises.org/catalog/
- O'Reilly: http://opds.oreilly.com/opds/
- Plough Publishing: http://www.plough.com/ploughCatalog_opds.xml
- PragPub Magazine | The Pragmatic Bookshelf: http://pragprog.com/magazines.opds
- Project Gutenberg: http://m.gutenberg.org/ebooks.opds/
SamEnrico: http://www.samenrico.com/(dead as of May 5, 2016 or earlier)
- Ebook Bike (formally TUEBL): https://ebook.bike/catalog
- The anarchist library: https://theanarchistlibrary.org/opds
- My Little Pony: https://mylittleserver.nl/fimfic/opds/
 (Mainly) Chinese
- Shucang: http://www.shucang.org/s/
SNDA YZSC: http://opds.yzsc.com.cn(dead as of May 5, 2016 or earlier)
 (Mainly) French
- Gallica: http://gallica.bnf.fr/opds
- OpenEdition (Livres et Revues): http://opds.openedition.org/
- Ebooks libres et gratuits: http://www.ebooksgratuits.com/
- Atramenta: http://www.atramenta.net/opds/catalog.atom
- YouScribe: http://opds.youscribe.com/Catalog/catalog.xml
- eForge: http://eforge.eu/OPDS/_catalog/index.xml
- Atoll Digital Library: http://atoll-digital-library.org/opds/
 (Mainly) Polish
 (Mainly) Russian
- Полнотекстовый поиск книг FBSearch: http://fbsearch.ru/opds/
- Электронные книги на русском: http://iknigi.net/opds
- Флибуста Книжное братство (EmerCoin, Tor): http://flibusta.is/opds
- Либрусек (Русские электронные книги): http://lib.rus.ec/opds
- Гейт OPDS для журнала "Самиздат": http://opdshome.uo1.net/samlib/
Book Library: http://books.vnuki.org/opds.xml(dead as 10/7/14)
- ePubBooks.ru (Русские электронные книги): http://www.epubbooks.ru/index.xml
- zone4iPhone.ru (Русские электронные книги): http://www.zone4iphone.ru/catalog.php
- КулЛиб (Русские электронные книги): http://coollib.net/opds
- maxima-library.org http://maxima-library.org/opds
- OPDS Start Page (Contains links to many other OPDS catalogs): http://opdshome.uo1.net/
 eBook Reading Software Supporting OPDS
In general, ODPS-client apps which support iOS standard inter-app communication methods, including sending files to other apps, can serve as download proxies for other iOS reader apps installed on the same device.
- Aldiko: - EPUB reader and OPDS client for Android and iOS
- AlReader: - any text book reader for Android
- Book Bazaar Reader: - ePub, FB2, Mobi reader/speaker, OPDS, Microsoft Edge, OneDrive client for Windows 8 available in the Windows 8/10 Store.
- BookMaster CE: - EPUB reader, OPDS and HTML client for iOS
- BookMaster SE: - EPUB and PDF reader, OPDS and HTML client and server for iOS
- Bookviser: - EPUB/FB2/TXT reader and OPDS client for Windows Phone and Windows 8
- Coffee Reader: - txt/ePub/Fb2/Mobi reader for Windows Phone 8 available on Windows Phone Marketplace.
Cool Reader: - Only in Android version.(dead as of May 5, 2016 or earlier)
- Document Viewer: - PDF, epub, FB2, CBZ for Android available in Google Play store and F-Droid.
- eBook Search: - No built-in reader, OPDS client for iOS, as a proxy for other reader apps, from the same developer of MegaReader
- eBook Search Pro - No built-in reader, OPDS client for iOS, as a proxy for other reader apps, from the same developer of MegaReader
- EPUBReader: - All devices and OS supporting Firefox and SeaMonkey Web Browsers
- FBReader: - All devices with network access.
- iBouquiniste: - iBouquiniste for iPad, iPhone, and iPod Touch. Supports FB2, ePub. Available on iTunes app store.
- IDEAL Group Reader: - ePub reader for the Android available in the Google Play store.
Infinite Book Reader: - eBook reader for the iPad.(dead as of May 5, 2016 or earlier)
- KOReader: - An ebook reader application supporting PDF, DjVu, EPUB, FB2 and many more formats, running on Kindle, Kobo, PocketBook, Ubuntu Touch and Android devices. Supports OPDS catalogs.
- Librera: - Book Reader application for Android supporting PDF, EPUB, EPUB3, MOBI, DJVU, FB2, FB2.ZIP, TXT, RTF, AZW, AZW3, HTML, XPS, CBZ, CBR and OPDS Catalogs.
- Mantano Reader: - EPUB and PDF reader for Android and iOS
- Marvin: - EPUB reader, OPDS client for iOS
- MegaReader: - EPUB reader, OPDS client for iOS with Heads Up Display.
- Moon+ Reader Pro: - ebook reader for Android devices.
Ouiivo Reader: - EPUB reader and OPDS client for iPhone and iPod Touch(dead as of May 5, 2016 or earlier)
- QuickReader: - EPUB speed-reading reader for iOS, from the same developer of MegaReader
- Stanza: - EPUB and PDF reader, OPDS client for iOS, and pioneer of OPDS Catalog. No longer available on the App Store.
- tiReader: - Reader for eBooks (epub2/epub3, pdf, djvu, fb2, mobi, prc, azw), Audiobooks (M4B, M4A, MP3) and Comics (cbr, cbz). OPDS and Calibre client. iOS.
 Software Supporting OPDS
- Calibre2opds compatible software - Calibre software is free
- personalbookspace: - A fee-based personal online catalog service
- AmuseWiki - a CMS which produces EPUB and OPDS catalogs out of the box
 OPDS Catalog Generation
- BookMaster SE: - automatically generates OPDS and HTML catalogs for its own book library on any iPad model running iOS 8.0 or later.
- calibre: - automatically generates OPDS and HTML catalogs for its own book library on Windows and Mac.
- calibre2opds generates OPDS and HTML catalogs from the ebooks database of Calibre.
- COPS generates OPDS and HTML catalogs on your server, from your Calibre library. Needs PHP and file access to the Calibre library.
- Lucicat generates OPDS and HTML catalogs on your server. Needs PHP/MySQL to run. As of mid-2012, the author has removed it from his website and it is unavailable, but here is a mirror
- OPDS catalog (Nextcloud) and OPDS catalog (Owncloud) is an app for the Nextcloud and Owncloud personal cloud server, enabling users to publish a sub-tree of their personal filesystem as an OPDS feed
- Pathagar - Pathagar is a book server written in Python Django. It serves book catalogs through a web interface and OPDS feeds for use with clients including the Get Books activity on the Sugar Learning Platform, largely used on One Laptop per Child laptops. Book uploads, tagging, grouping and other management is done through the web interface. Bulk uploads are done using JSON and CSV.
- Simple OPDS - Simple OPDS server for Linux platform written on python3
- TinyOPDS - lightweight and simple OPDS server for the home use, needs Windows OS plus .NET 4.0 (client profile) or Linux OS plus Project Mono
- Ubooquity is an ebooks/comics server which allows access to your collection through web pages or OPDS feeds. Needs Java.
 OPDS Catalog Validator
There is an easy-to-use online validator to help validate any OPDS catalog.