The backbone of Stump! There are a couple key concepts to go over regarding how Stump represents books:

  • Books (also internally referred to as media) primarily refer to files on disk
  • Books are grouped into series, which are then grouped into libraries
  • Metadata is an associated set of information about a book, such as its title, author, etc.

Supported formats

The following table outlines the supported formats for books in Stump:

ZIP Archive.cbz .zip
RAR Archive.cbr .rar
EPUB.epubEpub files aren't generally supported by ODPS-PSE (streaming) unless they are image-only. They are otherwise OPDS-compatible
PDF.pdfPDFium (opens in a new tab) is used for PDF-to-image rendering. Outside of Docker, you will have to provide Stump the location of your PDFium binary in order for PDF rendering to work. See configuration for more information.
  • Basic: Basic support encapsulates the minimally viable functionality for a given format. In general, this will include things like:
    • File discovery
    • Metadata extraction
    • File serving
  • Streaming: Streaming support refers to the ability to stream a book's pages individually to a client. This is generally important, as it reduces overall network loads by only sending the pages that are being requested by the client. If a format does not support streaming, the entire book will be sent to the client at once when it is requested.
    • Epub files are sort of an exception to this, as they are essentially an archive of HTML/CSS files. The HTML files for each chapter can currently be streamed individually, however the UI does not utilize this yet.
  • OPDS: OPDS support refers to the ability to serve a book according to OPDS. For more information, see the OPDS guide.


Metadata is an associated set of information about a book, such as its title, author, etc. Different formats have different ways of storing and representing metadata. Stump will attempt to extract as much metadata as possible from a given book, however it is not always possible. For example, PDF files do not generally have very good metadata support, and comic book files (e.g. CBZ/CBR) often times have very malformed metadata.

Sources per format

The following outlines the sources of metadata for each format:


Archive formats, aside from EPUB files, are primarily assumed to be comic books. As such, metadata is extracted from a file named ComicInfo.xml if it exists. Currently, Stump follows the v2.0 schema (opens in a new tab) for parsing. There is some leeway for malformed XML that Stump will try to catch, but it is not guaranteed to work. Please ensure your ComicInfo.xml is valid XML.


EPUB files typically store their metadata in an OPF file, but it is more limited than what can be found in a typical ComicInfo.xml file.


PDF files do not generally have very good metadata support. In general, I have seen only a few fields that are consistently populated, such as the title and author. PDF files are somewhat smelly 💩

Additional sources

Stump will also attempt to extract series metadata from a series.json file at the root of a series directory. This is not specific to any format or books in general, though, so refer to the series guide for more information.

Special metadata fields

There are a few special metadata fields that Stump will use for additional functionality:

Age rating

The age rating field can be used in-conjunction with access controls to restrict access to books based on their age rating. There are a LOT of different age rating systems, and Stump does not currently support all of them, so be sure to review the age restriction section for more information.