(registered 2026-10-27, last updated 2026-10-27)

Media type name: application

Media subtype name: vnd.ngdtuanh.abook+zip

Required parameters: N/A

Optional parameters: N/A

Encoding considerations: binary

Security considerations: The file is a ZIP archive of audio (MP3 or WAV; background-music tracks the user imported may also be M4A, Ogg, Opus or FLAC), a JPEG cover and JSON metadata, plus, in version 4, an optional listener edit layer (edits.json, at most 1 MiB, and edits/cover.jpg, a JPEG of at most 8 MiB). It contains no executable or active content and no external references. Readers must reject entry names outside the fixed list in the specification (no absolute paths, no ..), enforce limits on entry count and sizes against decompression bombs, and verify every entry's size and SHA-256 against book.json. Media payloads are handed to the platform's standard decoders. The format carries no personal data about the listener.

Interoperability considerations: The first ZIP entry is mimetype, stored uncompressed, containing the media type string, so the format can be identified from the first bytes (as in EPUB). The archive also contains a Readium Audiobook manifest (manifest.json) so other audiobook players can read the audio.

Published specification: https://github.com/ntanhpro1221/ABook/blob/main/_internal/docs/ABOOK_FILE_FORMAT.md

Applications which use this media: ABook, an audiobook production and listening app for Windows and Android (https://github.com/ntanhpro1221/ABook)

Fragment identifier considerations: N/A

Restrictions on usage: None

Additional information:

1. Deprecated alias names for this type: N/A
2. Magic number(s): PK\x03\x04 at offset 0; the ASCII string mimetypeapplication/vnd.ngdtuanh.abook+zip at offset 30
3. File extension(s): .abook
4. Macintosh file type code: N/A
5. Object Identifiers: N/A

Person to contact for further information:

1. Name: Nguyễn Duy Tuấn Anh
2. Email: ntanhpro1221&gmail.com

Intended usage: COMMON

Author/Change controller: Nguyễn Duy Tuấn Anh