Fathom vs Kavita and Komga

The question is where your books already live

This comparison has a short answer that is right most of the time: if your books are already in Jellyfin, try Fathom first. If they are not, run Kavita or Komga.

Everything below is about the cases where that shortcut is wrong.

What Fathom is, structurally

Fathom is not a reading server. It has no scanner, no metadata database, no user table and no library of its own. It reads Jellyfin’s reading libraries over the API and renders them.

That is a genuine limitation and also the entire point. There is no second scan to schedule, no second database to back up, no second set of accounts to keep in sync with the first, and no second thing to upgrade. One Jellyfin account covers the films, the music and the books.

The cost is that Fathom can only be as good as Jellyfin’s model of a reading library. Where Jellyfin is thin, Fathom is thin.

What Kavita and Komga are

Both are complete reading servers, and both are clearly better at reading than Jellyfin is.

Komga is strongest on comics and manga. Its series, volume and chapter handling is purpose-built, its CBZ and CBR support is thorough, and its reader is tuned for page-by-page reading including right-to-left.

Kavita is broader — comics, manga and ebooks in one server, with a good EPUB reader, reading lists and solid per-user progress.

Both serve OPDS, which matters more than it sounds: it lets KOReader, Panels, Chunky and similar apps connect directly. Fathom has no OPDS.

The real trade

Running a second server is not free. It is a second container, a second database, a second backup, a second upgrade path, a second set of users, and a second place to look when something is missing. None of that is hard; all of it is ongoing.

If your reading collection is a hundred books that you dip into occasionally, that overhead outweighs the better reader you get in return, and Fathom is the proportionate answer.

If you have four thousand manga chapters and read daily, the overhead is trivially worth it and Komga’s series handling alone will justify it within a week.

Most people know which of those they are.

Where Jellyfin’s model shows its limits

Worth being concrete, since this is where the comparison actually bites.

Jellyfin treats a book roughly as it treats any other library item. That works fine for standalone ebooks and PDFs. It works less well for a manga series with sixty volumes and a thousand chapters, where the hierarchy — series, volume, chapter — carries most of the meaning and Komga models it explicitly.

Fathom cannot fix that from the client side. It presents what Jellyfin knows. A cover-first grid over a large manga collection with weak series metadata is still a cover-first grid over weak metadata.

For books, PDFs and comics without deep series structure, the gap is much smaller and Fathom’s browsing experience is pleasant.

Trying Fathom

It is one container and it changes nothing on the server:

services:
  fathom:
    image: getcoral/fathom:latest
    restart: unless-stopped
    depends_on: [jellyfin]
    ports:
      - "3003:3000"
    environment:
      FATHOM_DATA_DIR: /data
      JELLYFIN_URL: http://jellyfin:8096
      JELLYFIN_API_KEY: ${JELLYFIN_API_KEY}
      JELLYFIN_USER_ID: ${JELLYFIN_USER_ID}
    volumes:
      - ./fathom-data:/data

Because Fathom stores nothing but its own connection details, evaluating it costs one container and abandoning it costs nothing. If it turns out your collection wants a real reading server, Kavita and Komga are both excellent and neither project will mind.

See the Fathom module page for full configuration. For keeping the metadata on those books in order, Librarian works on Jellyfin libraries generally.