How to merge PDF files into one

To merge PDF files, open the first one at pdfviewer.work, click Merge and choose the second file; its pages are appended to the end. Repeat for more files, drag thumbnails to reorder, then click Download. The combined PDF is built in your browser and nothing is uploaded.

Merge PDF files in five steps

1. Open the file that should come first. Drop it here or on the merge tool page, or click Open a PDF.
2. Click Merge and pick the next PDF. Its pages are added after the last page of the current document.
3. Repeat for every file you want in the bundle. There is no cap on the number; the limit is your browser's memory.
4. Fix the order. In the thumbnail sidebar, drag any page to a new position, rotate a sideways page, or delete a cover sheet you do not want. Details: reorder PDF pages.
5. Click Download. One PDF, in the order you see in the sidebar.

Opened the wrong file first? Merge appends, so the quickest fix is to reload, open the right file and merge again, or just drag the pages into place.

What happens to the pages when you merge

Merging copies pages from the second file into the first, as they are. A landscape page stays landscape, a scanned page stays a scan, a page with annotations keeps them. The combined document is written with pdf-lib when you download; the two source files on your disk are not modified.

Two things do not carry over: form fields remain visible but are not editable in the viewer, and bookmarks (the outline panel some readers show) are not merged. If you need an outline across a 300-page bundle, Acrobat or a command-line tool is the better fit. For adding a separator page between documents, use add a blank page, then drag it into position.

How to merge PDFs on Mac, Windows and the command line

• Mac: open both PDFs in Preview, show thumbnails (View, Thumbnails), and drag pages from one sidebar into the other; then File, Export as PDF. It works but is fiddly with many files.
• Windows 11: there is no built-in merge. Acrobat Reader prompts for a subscription; Microsoft Print to PDF cannot combine files. The browser viewer is the quickest no-install option.
• Linux and the command line: qpdf --empty --pages a.pdf b.pdf c.pdf -- merged.pdf or pdftk a.pdf b.pdf cat output merged.pdf. Scriptable and fast for hundreds of files.
• Online services: iLovePDF and Smallpdf merge well, but they upload every file to their servers. Fine for a brochure, questionable for payslips or medical records.

Preparing files before you merge them

A merged document is only as tidy as its parts. Open each file on its own first and clean it: rotate sideways scans, delete blank backs from a duplex scanner, remove fax headers and cover sheets. Each cleanup is a click on the thumbnail, and you download a clean copy before moving on. Then merge the clean copies, so you are not hunting for stray pages in a 150-page bundle.

Mixing scans and born-digital PDFs is fine; the result simply has searchable and non-searchable pages side by side. If the whole bundle must be searchable, run OCR once on the merged file rather than on each part; the OCR guide covers timing. For a bundle that will be printed, click Print after merging and the browser dialog prints it as one job.

File size adds up: the merged PDF is roughly the sum of its parts, and the viewer does not compress. If the result must fit an email limit, reduce the heavy scans before merging.

Troubleshooting merged PDFs

• One of the files asks for a password. It cannot be merged until the open password is removed; see remove a password from a PDF.
• The tab slows down or crashes. Several large scans add up to hundreds of megabytes in memory. Merge on a laptop rather than a phone, and close other tabs.
• Pages came in sideways. Click the rotate control on the thumbnail; each click turns the page 90 degrees.
• You need to split the result later. The viewer has no split, but deleting the pages you do not want and downloading is the workaround; the split PDF page lists other tools.

Frequently asked questions