Love Zotero for citations,but want a real PDF reading experience?

Zotero 7 added a built-in PDF/EPUB/HTML reader with highlighting and annotation, and it's a genuine step up. But Zotero's center of gravity is still references, libraries, and bibliographies, the reading view is there to support citation work. If you want reading-first features like page-flip (book-like) layout, vertical scroll, and right-to-left mode for manga, that's PDFBook's whole job, not Zotero's.

Zotero itself is free, and you can keep an unlimited local library or use WebDAV / linked-file attachments to avoid paying anything. But Zotero's own File Storage gives 300 MB free, then 2 GB for $20/year, 6 GB for $60/year, or unlimited for $120/year (per zotero.org/storage, as of June 2026). PDFBook never syncs your PDFs to a paid cloud, files stay in your folders, so there's no per-GB storage bill at all.

Zotero stores your items, notes, and PDF annotations in its own SQLite database (annotations sync across desktop/iOS/Android). That's great for a citation manager. PDFBook takes a deliberately lighter approach: it never modifies your PDFs, and your library metadata, folders, tags, ratings, reading state, bookmarks, and a per-book note, lives in a plain-text library.json you can read, back up, or grep yourself.

If your day is inserting citations into a manuscript and exporting a bibliography, Zotero is the right tool and PDFBook won't replace it. If your day is reading dozens of PDFs and EPUBs and keeping them organized, that's where PDFBook fits. Many people use both: Zotero as the citation database, PDFBook as the reader they open every day.