EPUB Metadata Editor

This tool edits the bibliographic metadata stored inside an EPUB's package (OPF) file: the Dublin Core fields that e-readers, library catalogs, and storefronts read to identify a book. It is meant for the moment after a book is built or acquired but before it is shelved or shipped: correcting an author name that imported wrong, setting a publisher line, fixing a missing or incorrect language code, or pasting in a proper description blurb.

Typical cases: self-publishers matching the title and rights line to their store listing, librarians making titles and authors display consistently, and anyone fixing files that show 'Untitled' or 'Unknown Author' on a tablet.

The flow is: drop or select a .epub file, let it parse, edit the form, then click Save and download EPUB. On load the tool reads the package file and pre-fills eight fields: Title (required), Author, Publisher, Language, Publication date, Rights/Copyright, Subjects (comma-separated) and Description. On save it rewrites the matching Dublin Core elements (dc:title, dc:creator, dc:publisher, dc:language, dc:date, dc:rights, dc:subject and dc:description), refreshes the EPUB 3 modified date, repacks the ZIP with the mimetype file first, and gives you a new file with an '-updated' suffix. Your original is left untouched.

Language expects a BCP 47 tag (for example en, en-US, fr, de), and the date is free text where an ISO form like 2024-01-15 is the safe choice. A field that was missing in the original is created; clearing an optional field removes it, while the required title and language are never removed. Subjects replace the book's existing subject list, one dc:subject per comma-separated entry. The Save button stays disabled until Title has a value.

What it does not do: it does not edit the identifier (ISBN or UUID), subtitle, series or contributor roles, it does not touch the cover, chapters or layout, it does not convert formats, and it does not check that your language tag or date are well-formed.

DRM-protected files cannot be edited; the tool detects the protection and stops with a clear message rather than producing a broken file. It also only opens genuine EPUB ZIPs; a renamed or corrupt file will be rejected. Very large illustrated EPUBs may be slow or refuse to load on low-memory devices, since the whole book is repacked in the browser.

The most common mistake is expecting a field that is not there: an ISBN, a series or a subtitle live in elements this editor does not write. A second pitfall is the Author field: it edits the first dc:creator only, so in a multi-author book the other authors stay as they were, and file-as or role information is not edited.

Also note that values are written as plain text; the tool does not strip stray HTML you paste into Description, normalize smart quotes, or remove duplicates if the original package already had several title or creator entries. Garbage in is preserved as-is.

After downloading, open the '-updated.epub' in the actual target (your e-reader app, Calibre, or the FormatOS EPUB Inspector) and confirm the title, author, publisher, language, date, rights, subjects and description all show the values you entered, with correct accents and capitalization. Check that the file still opens and pages normally, since repacking touches the whole archive.

If you are targeting a specific store, run the file back through the relevant checker (Kindle, Apple Books, or Kobo) to confirm your changes did not leave a required field empty. Keep your original until you have confirmed the new file is sound; the tool writes a separate copy so you always have a fallback.

For an ISBN-registered publication or a contractual deliverable, confirm the rights line, publisher and dates against your own records.