Combining PDF Files into One Document
What this tool does
A PDF merger takes several separate PDF files and stitches them into a single document, copying every page from each source file in turn. This tool loads each PDF you add, reads its pages with pdf-lib, and writes them one after another into a new file — file one first, then file two, and so on down the list. The page content, embedded fonts, and images from each original are carried into the combined result, so a report and its appendix end up as one continuous document you can share or archive as a single unit.
Nothing about the individual PDFs is altered; the merge only concatenates them. What changes is that instead of juggling five attachments, you hand over one.
When to use it
Merging is the natural last step whenever a deliverable is spread across files. Scanned pages that arrived as separate documents, a cover letter followed by a CV, chapters exported one at a time, or a batch of invoices for a single month all read better as one file. It is also handy before printing, since a single PDF prints in the right order without you reopening each document.
Because you control the sequence, the tool doubles as a way to reassemble pages that were split apart — put the files back in their original order and merge.
Example: a report in three parts
Say you have cover.pdf, body.pdf, and appendix.pdf. Add all three, then use the move-up and move-down buttons until the list reads cover, body, appendix from top to bottom. Give the output a name like report-final.pdf and merge. The result opens with the cover page first and the appendix last, its total page count equal to the sum of the three inputs. Reorder the list and merge again to get a different arrangement without touching the source files.
Notes and edge cases
The order in the file list is exactly the order pages appear in the output, so arrange the list before merging. Up to 20 files of 50MB each can go into one job; very large batches merge faster in smaller groups. Page-level content transfers reliably, but document-level extras such as bookmarks (outlines), form fields, and some metadata may not survive, since the merge rebuilds a fresh document from the copied pages. Password-protected PDFs must be unlocked first — an encrypted file cannot be read for merging. The whole operation runs locally with pdf-lib, so confidential contracts never leave your device.