Combine PDFs and reorder their pages in Preview
Merging documents, moving pages and deleting the ones you do not need all happen in the sidebar.
Works on: macOS Big Sur 11 and later · checked on macOS Golden Gate 27
Published: · Source: Apple
Everything happens in the sidebar, so start with View → Thumbnails.
Combine. To add a whole PDF, drag its icon from the Finder onto the sidebar of the open document, between the pages where it should go. To take only some pages, open both PDFs with thumbnails showing and drag the pages you want from one sidebar to the other.
Reorder. Drag thumbnails to their new position. In a long document, View → Contact Sheet shows the pages large enough to see what you are moving.
Delete. Select the thumbnails and press Delete.
One warning: Preview saves changes automatically, and combining changes the document you add pages to. Duplicate the originals first if you need to keep them.
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