ENES
By Liber Team··Updated on July 28, 2026·7 min read

What is OPDS? Add Custom Book Sources to Your eBook Manager

OPDS is an open protocol that turns any book server into a browseable catalog — like an RSS feed for books. Here's how it works, where to find OPDS servers, and how to use them in your eBook manager.

What is OPDS? Add Custom Book Sources to Your eBook Manager

If you configure a self-hosted book server or access an institutional digital catalog, you will frequently encounter the OPDS protocol. The concept is straightforward: OPDS serves a function for digital books analogous to RSS for syndicated web content. It provides a standardized method for publishing catalogs of books that applications can browse and download.

Getting OPDS right in a reading app is the difference between browsing a remote library and downloading files one by one.

What OPDS Actually Is

OPDS (Open Publication Distribution System) is basically RSS for books. Under the hood it’s an Atom feed with extensions for digital publications, and its job is to let a reading app browse and download books from any compatible server.

Because OPDS is an open standard, it is implemented across a variety of platforms:

  • Calibre-Web — a self-hosted web interface for Calibre libraries
  • Kavita — a self-hosted server for manga, comics, and books
  • Komga — a self-hosted server for comics and books
  • Polar Bookshelf, KOReader, Aldiko, and numerous other reading applications
  • Public libraries — institutional systems frequently expose OPDS feeds for their digital collections
  • Standard Ebooks and other curated digital archives

An OPDS catalog URL generally follows this structure: https://yourserver.local:8083/opds

When configured in a compatible eBook manager, this URL provides a structured interface, enabling search functionality, category browsing, and direct file retrieval.

OPDS vs Downloading Manually

Without OPDS: Acquiring a file from a Calibre-Web server to a local device requires several manual operations:

  1. Open a web browser
  2. Navigate to the server address
  3. Locate the file
  4. Initiate download
  5. Open the local eBook manager
  6. Import the downloaded file
  7. Transfer to the reading device

With OPDS integration: Within a compatible eBook manager:

  1. Open “Custom Sources”
  2. Browse the server catalog directly
  3. Select “Add to Library”

The file is imported immediately. This protocol integration removes intermediate file management and application switching.

The Two Versions of OPDS

OPDS 1.x is the initial standard. It relies on XML (Atom) and maintains near-universal support among OPDS-aware applications. Systems like Calibre-Web, most institutional libraries, and legacy servers utilize this version.

OPDS 2.0 is the revised standard, utilizing JSON rather than XML. This alteration provides faster parsing and expanded feature support, including integrated cover images within catalog entries. Software such as Kavita (0.8+) and Komga support OPDS 2.0. Adoption is increasing but remains incomplete.

If a server supports both protocols, OPDS 2.0 offers measurable performance advantages. If a client application is restricted to OPDS 1.x, it will still function with the vast majority of active servers.

Public OPDS Sources (No Server Required)

You don’t need to run a server to use OPDS. Several public catalogues are open to anyone:

Standard Ebooks — https://standardebooks.org/feeds/opds Public domain classics, re-edited with more typographic care than anywhere else. Mostly EPUB.

Project Gutenberg — https://gutenberg.org/ebooks.opds/ The original ebook archive: over 70,000 public domain titles.

Feedbooks — https://www.feedbooks.com/books/recent.atom A mix of public domain works and independent authors, in EPUB and PDF.

Public library systems — Many municipal and academic libraries in the US, UK, and Europe maintain OPDS catalogs for registered patrons.

Setting Up a Self-Hosted OPDS Server

If you already have a Calibre library and want to reach it from outside the house, Calibre-Web is the usual answer.

Calibre-Web (github.com/janeczku/calibre-web) is a web interface that provides:

  • A browser-based UI for library management
  • An OPDS 1.x feed accessible at /opds
  • Send-to-Kindle integration

Basic setup (Docker):

docker run -d \
  --name calibre-web \
  -p 8083:8083 \
  -v /path/to/calibre/library:/books \
  lscr.io/linuxserver/calibre-web:latest

The resulting OPDS endpoint will be located at http://your-machine:8083/opds.

Kavita (kavitareader.com) is an alternative implementation optimized for image-based formats such as manga or comics.

Komga (komga.org) offers similar functionality to Kavita and is supported by an established user base.

OPDS with Authentication

Most private servers require basic authentication to restrict access. Configuration within a client application typically requires three parameters:

  • URL: https://yourserver.com/opds
  • Username: The server username
  • Password: The server password

The client application manages the authentication credentials, allowing continuous catalog access without repeated login prompts.

Security note: For servers exposed to the public internet, HTTPS is mandatory. Network tunneling services such as Tailscale or Cloudflare Tunnel generally manage SSL/TLS certificates automatically.

OPDS in Practice: Operational Workflow

Say you keep your manga on a Kavita server at home and you want to read it on your laptop.

Without an OPDS client:

  1. Open a browser, navigate to the Kavita instance, and search for the volume
  2. Download the relevant files (e.g., CBZ format)
  3. Open the local management application and import the files manually
  4. Locate the imported files within the local directory

With an OPDS client:

  1. Navigate to Custom Sources within the management application and select Kavita
  2. Search for the volume
  3. Select “Add to Library”
  4. The files are retrieved and cataloged automatically

The OPDS workflow circumvents manual file system operations.

OPDS Integration in Liber

Most OPDS clients render a catalogue as what it technically is: an XML list of links. It works, but it feels closer to an FTP directory than to a bookshop. In Liber, a remote catalogue looks like the rest of your library.

  1. It reads like a shelf, with covers and the same grid as your local books — not like a list of links.
  2. One click to own it. Browse a connected server (Kavita, Komga, Calibre-Web), tap a book, and it lands in your library with its metadata — no trip through the Downloads folder.
  3. Tuned connections for Kavita and Calibre-Web, on top of generic OPDS, so covers and metadata arrive quickly.

If you already run a server, Liber is the client for it. And if you’d rather start with public catalogues, Standard Ebooks and Gutenberg are built in — see how it compares to the alternatives.