How to merge PDF files without uploading them

Why it can matter where your PDFs go

Many online PDF services work by uploading your files to a server, combining them there and sending the result back. For a restaurant menu that does not matter much. For a tax return, a contract, medical records, a passport scan or a set of payslips, it can. Once a file is on someone else's server, you depend on their promises about how long it is kept, who can see it and where it is stored.

Some employers and clients also forbid sending confidential documents to outside services at all. Merging on your own device avoids the question: the files are read from your disk, combined in memory and saved back to your disk. Every method below works that way.

Merge PDFs on a Mac with Preview

Preview, the PDF and image viewer built into macOS, can combine PDFs without any extra software. Preview saves changes into the file you opened, so work on a copy (File > Duplicate) if you want to keep the original unchanged.

1. Open the first PDF in Preview.
2. Choose View > Thumbnails to show the page sidebar.
3. Drag another PDF from Finder onto the sidebar, or drag single pages from another open Preview window, and drop them where they should go.
4. Drag thumbnails up or down to fix the page order.
5. Save the result, or choose File > Export as PDF to write a new file.

Merge PDFs with Adobe Acrobat

Adobe Acrobat has a Combine Files tool that joins PDFs, and also other documents such as Word files and images, into one PDF. You add the files, arrange them and click Combine. Combining is part of Acrobat's paid tools; the free Acrobat Reader is for viewing, filling in and signing PDFs. If your workplace already has Acrobat, it is a good choice for large jobs and for keeping bookmarks.

Merge PDFs on the command line with qpdf

qpdf is a free, open source program for Linux, macOS and Windows. It is available through most Linux package managers and Homebrew on a Mac. This command creates a new, empty PDF and adds all pages of a.pdf and then b.pdf, writing the result to out.pdf. List as many input files as you need before the two dashes.

qpdf --empty --pages a.pdf b.pdf -- out.pdf

Merge PDFs on the command line with pdfunite

pdfunite comes with poppler-utils, a set of PDF tools installed on many Linux systems or available from the package manager (on a Mac, Homebrew's poppler package includes it). The last file name is always the output, so check it before you press Enter. Command line tools are the best option when you merge files regularly or want to script the job.

pdfunite a.pdf b.pdf out.pdf

Merge PDFs in your browser with FileReshape

If you are on a Windows PC, a Chromebook or a computer where you cannot install software, FileReshape's Merge PDF page does the job in the browser. The page loads a PDF library into the browser tab, and your files are combined there on your own device. They are not uploaded to a server, and there is no watermark and no fixed page limit; your browser's memory sets the practical limit.

Pages are copied unchanged, so text stays selectable and searchable, links keep working and every page keeps its own size. Files are added one after another, with all pages of each file. To change the order of single pages afterwards, or to rotate or remove pages, open the merged file in the Organize PDF tool.

1. Open the Merge PDF page and drop two or more PDF files in the box, or click to choose them.
2. Use the arrows to put the files in the order you want.
3. Click Merge PDFs and download merged.pdf.

Limits to know before you merge

FileReshape's merge does not carry over bookmarks or the table of contents of the original files. Filled-in form fields show their values, but the merged file is no longer a fillable form. A digital signature becomes invalid, because the signed document has changed, so merge first and sign the combined file. Password-protected (encrypted) PDFs cannot be merged; open them in your PDF reader, save a copy without the password and add that copy instead.

When bookmarks or a working form matter, Acrobat is the better choice. If the merged file is too large to email, run it through a PDF compressor afterwards.