Choose files and establish page order before merging
A merge normally appends every page from the first document, then every page from the second, and so on. Rename or arrange files deliberately, and use first-page previews as orientation rather than assuming alphabetical file order is correct.
- Check the first and last page of each source.
- Place cover sheets and appendices intentionally.
- Keep an untouched copy of every source.
Mixed page sizes do not need to be normalized
PDF pages can have different dimensions and orientations in one document. Page copying can preserve Letter, A4, portrait, and landscape pages without rasterizing them. A viewer may fit each page differently on screen, and printing may require an explicit scaling choice.
Merging changes the document structure and signatures
A cryptographic digital signature covers a particular document state. Copying signed pages into a new PDF generally does not preserve that signature as a valid signature on the merged file. Bookmarks, forms, attachments, and document-level navigation may also require separate review.
Know whether a merger uploads the documents
A browser-local workflow keeps document bytes on the device during processing, while a server workflow sends files to another system. Either model can be appropriate, but confidential files require a deliberate choice and a review of the service's retention terms.
After merging, reopen the download and verify page count, transitions between source files, mixed orientations, and the final page before distributing it.