Review the package metadata
EPUB books are ZIP containers with package metadata, pages, images and styles. Optional metadata can name creators, contributors, publishers, editing software and dates. Select which supported fields to remove, then review the original metadata in the local report.
Keep the book structure
The output keeps the required title, language and unique identifier, along with EPUB 3 modification metadata. It puts the uncompressed mimetype entry first. Authored pages, images and styles stay byte for byte; only selected package metadata and ZIP headers change. The uncompressed output may be larger.
External-reference candidates in supported text attributes and CSS are listed without visiting them. They stay in the book. Generated or obfuscated URLs can be missed, so this is not a complete network audit.
What this does not remove
Watermarks, purchaser details in book pages and identifiers can remain. Encrypted, DRM-protected, font-obfuscated and signed EPUBs are unsupported. The limits are 32 MiB input, 64 MiB expanded and 1,000 entries. Nothing is uploaded.