Merge PDFs
What Merge PDFs actually does
Most merge tools quietly throw away the parts of a PDF that are not pages. Bookmarks vanish, form fields stop working, and the title and author of the merged file become whatever library wrote it. This workspace shows every page of every document in the order it will be written, carries the bookmark tree across and remaps it to the pages that survived, relists the form fields so a reader still sees a form, and writes the document details supplied rather than inherited. The same documents with the same settings produce the same bytes every time.
How to use it
- Add up to 20 PDFs totalling 200 pages. Each one is read locally and reports its page count, bookmarks, form fields, and page sizes before anything is combined.
- Work the page board: move documents or individual pages, leave pages out, and turn any page in quarter steps. Every control is a labelled button or select, so no dragging is needed.
- Choose whether to keep every bookmark, create one bookmark per document, or remove them, set the title, author, subject, and keywords, then merge and download the PDF with a JSON receipt.
Useful for
- Combine a report, its appendices, and a signed cover sheet while keeping every bookmark pointing at the right page.
- Build a packet from selected pages of several documents rather than whole files.
- Produce a merged file whose title, author, and dates are set deliberately and reproducibly.
Limits worth knowing
- The browser accepts up to 20 unencrypted PDFs, 50 MiB each, 200 pages in total, and 250 MiB of output. Encrypted or unreadable files are named and refused rather than partly merged.
- Digital signatures do not survive any merge. Attachments, page labels, tagged structure, optional content groups, and links that point between the original documents are not carried.
- Form fields are relisted from the widgets that landed on the kept pages, and fields sharing a name across documents are renamed so their values do not link. Complex or shared field resources are not reconciled.
- Page sizes and rotations are preserved per page. Nothing is scaled to a common size.
Questions people ask
Does merging PDFs lose the bookmarks?
It does in most tools, and it did in this one before this release. The merge now rebuilds the bookmark tree in the output and points every entry at the page it followed. Bookmarks whose page is left out are dropped rather than left pointing somewhere wrong, and the receipt reports how many each document carried.
Can I merge only some pages of a document?
Yes. The page board lists every page of every document and any page can be left out or moved. The result is exactly the pages shown, in the order shown.
What happens to fillable form fields?
The widgets on the kept pages keep their values and appearances, and the merged file gets a form dictionary again so a reader can see them. Fields with the same name in two documents are renamed so filling one does not fill the other.
Will the same files always produce the same merged PDF?
Yes. Creation and modification dates are pinned rather than taken from the clock, so the same documents with the same page plan and settings produce a byte-identical file.
Is the PDF uploaded?
No. After this page loads, reading, thumbnails, merging, and downloads happen in this browser tab with locally bundled code.