OPDS Protocol (Servers & Clients)

OPDS — the universal protocol for self-host ebook stores; Calibre, KOReader, Moon+, FBReader all speak it.

OPDS (Open Publication Distribution System) is the open standard for ebook catalogues — think "RSS for books." Any OPDS server (Calibre, Calibre Web Automated, Komga, Kavita, Stump, Ubooquity, ABS for podcasts) can be browsed by any OPDS client (KOReader, Moon+ Reader, FBReader, Aldiko, Thorium, Panels, Chunky, Tachiyomi). It's how the FOSS book stack stays interoperable. Pair with Self-Host Libraries, KOReader, and Reader Apps.

Self-host & FOSS first

OPDS is the way to keep your ebook library portable across devices. No app lock-in, no account, just a URL + optional HTTP auth. Every meaningful FOSS ebook server speaks it.

What is OPDS

OPDS 1.x — Atom-based catalogue feeds (XML); universal client support; the de facto standard.
OPDS 2.0 — JSON-based; richer metadata; growing client support 2024-26.
OPDS-PSE — Page-Streaming Extension for comics / manga; Komga, Stump, Tachiyomi support.
Search / facets — OPDS includes OpenSearch for "find books by author X."
Auth — HTTP Basic / Bearer tokens; most clients store credentials per-feed.

OPDS servers (FOSS)

★ ★ Calibre Web Automated (CWA) — auto-imports + serves OPDS; the modern default. See Self-Host Libraries.
★ Calibre Content Server — Calibre's built-in OPDS endpoint; run calibre-server.
★ Calibre-Web — original Calibre-Web; OPDS + reader.
★ Komga — comics / manga; OPDS + OPDS-PSE.
★ Kavita — comics + ebooks; OPDS.
★ Stump — modern Rust-based; OPDS + OPDS-PSE.
Ubooquity — Java OPDS server; freeware (not OSS); long-running.
COPS — PHP front-end for Calibre libraries; lightweight OPDS server.
- https://github.com/seblucas/cops
calibre2opds — generate static OPDS catalogues from a Calibre library.
GNU FBReader Stream — community OPDS server.

OPDS clients (FOSS / free first)

★ ★ KOReader — free OSS (AGPL); Kindle / Kobo / Boox / desktop; native OPDS browser with per-catalogue auth and download. The default OPDS client for serious readers.
- https://github.com/koreader/koreader
★ FBReader — free OSS; Android / iOS / desktop; OPDS; long-running open-source default.
★ Thorium Reader — free OSS; desktop EPUB reader; OPDS feed subscription.
- https://github.com/edrlab/thorium-reader
★ Librera Reader (Android) — free + paid Pro; OPDS; very deep customisation.
Moon+ Reader (Android) — paid + free; OPDS; deep customisation; long-running favourite.
Aldiko Next — Android; OPDS.
Lithium — Android; OPDS.
Panels (iOS) — paid; OPDS comics reader; supports OPDS-PSE streaming.
Chunky (iOS) — paid; comics + OPDS.
Tachiyomi / Mihon (Android) — manga; Komga / Kavita / Stump extensions handle OPDS-PSE.
Komelia — community Komga desktop client; OPDS-aware.
Marvin (iOS) — long-running EPUB reader with OPDS (sunset-flavoured but still works).

Public OPDS catalogues

You can subscribe to other people's OPDS catalogues, not just your own:

★ Standard Ebooks OPDS — https://standardebooks.org/opds — beautifully typeset public-domain classics; subscribe in KOReader and you have a built-in classics shelf.
★ Project Gutenberg OPDS — full Gutenberg catalogue.
Feedbooks public-domain OPDS — clean catalogue of free EPUBs.
Internet Archive OPDS — community gateways exist (not official).
Smashwords OPDS — older indie catalogue.

Patterns

★ Run CWA + Komga behind a reverse proxy — you get one HTTPS URL per server; subscribe KOReader / Moon+ / FBReader once and your whole library appears.
★ Subscribe to Standard Ebooks — free, classy, instantly fills any device with curated classics.
Auth per-feed — most clients let you save credentials; HTTP Basic + HTTPS is fine.
Tailscale / WireGuard for off-network access — see VPN & Mesh — keep your OPDS server private but reachable from a Kindle on hotel Wi-Fi.
OPDS-PSE for manga — Komga / Tachiyomi; you don't have to download the whole CBZ to start reading.

Pick this if…

Default OPDS client (e-ink / cross-platform): KOReader.
Default OPDS server (ebooks): Calibre Web Automated.
Default OPDS server (comics / manga): Komga.
Lightweight OPDS server: Stump (or COPS for static / PHP).
Free polished public-domain feed: Standard Ebooks OPDS.
iOS comics OPDS: Panels or Chunky (paid).