Fix a book that shows up as untitled or by Unknown in your e-reader library
Processed in your browser. Nothing is uploaded. Checked against sources on 17 Oct 2026.E-readers sort and display books by the title and author stored inside the EPUB, not by the file name, so renaming the file changes nothing in the library. Drop the book here, correct the title and the authors, one per line, and save. Only the package document inside the book is rewritten; every chapter, picture and font is copied unchanged, so the book reads exactly as before.
Drop your files or click to choose them.
Adjust the options and check the preview.
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E-reader apps, Calibre libraries and online stores read a book's title and author from inside the EPUB file, not from its file name. A converted or self-published book often arrives as untitled_final_v2 by Unknown, with no language set, and renaming the file does not help.
The book's identifier is shown but never changed, because other parts of the book point to it. Title and language are required by the EPUB standard, so the Save button waits until both are filled, and the language code and date are checked as you type.
How the book is written. An EPUB is a zip archive with a package document listing its details. Only that one file is rewritten: the old entries for the fields above are removed, with any EPUB 3 refinements that described them, and the new values are written in. EPUB 3 books also get their required last-modified time updated. Every other file in the archive, chapters, images, fonts and styles, is copied byte for byte, and the mimetype file stays first and uncompressed, as e-readers expect.
The rest of the article, and all 6 questions about EPUB Metadata Editor, are on the EPUB Metadata Editor page.
Drop the EPUB on EPUB Metadata Editor. Its current title, authors and other details appear in boxes; type the right ones, with each author on its own line, and press Save EPUB with these details. E-reader apps then show the new title and author.
Many library apps keep a copy of the details they read when the book was first added. Remove the old book from the library and add the saved one, or ask the app to refresh its metadata. Renaming the file alone never changes the displayed title.
No. Only the package document that lists the book's details is rewritten. Every chapter, picture, font and style sheet is copied byte for byte, and the archive keeps the layout e-readers require, so the book opens and reads exactly as before.
No. The book is opened and rewritten by your own browser, and the new file is created on your device. Unpublished manuscripts stay private, and closing the tab removes everything.
Rates and rules change; check the source before you rely on a figure.
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