Two Ways to Merge PDFs on Mac
macOS includes Preview, a free PDF viewer and editor bundled with every Mac. Preview can merge PDFs, which means you do not need to install anything. However, Preview's merging workflow is clunky: you must open each PDF separately, drag its thumbnail into another PDF's sidebar, and repeat for every file. For two or three PDFs, it is manageable. For ten PDFs, it is tedious and error-prone.
The browser-based alternative—pdfmerger.io in Safari or Chrome—offers a faster, more visual workflow. You select all your PDFs at once, see a live preview of the merge order, and drag to reorder them before merging. For anyone merging more than three PDFs regularly, the browser approach is superior.
How to Merge PDFs in macOS Preview
Open the first PDF in Preview (right-click the file, select "Open With," and choose Preview). Look for the thumbnail sidebar on the left—if it is not visible, press Command+2 or go to View > Thumbnails. Now open a second PDF in a new window (File > Open, or Command+O). Navigate to the second PDF and open it.
In the new window showing the second PDF, click and drag the PDF's thumbnail from the sidebar into the first window's thumbnail sidebar, below the first PDF's thumbnails. You will see the thumbnail appear in the stack. Repeat this for each additional PDF. Once all PDFs are merged in the correct order, save the file: File > Save (or Command+S). macOS will save the merged PDF.
This workflow is clunky because you are managing multiple windows, dragging between them, and hoping you do not drop a thumbnail in the wrong place. The visual feedback is minimal, and reordering multiple files is error-prone.
How to Merge PDFs in Safari Using pdfmerger.io
Open Safari (or Chrome) and navigate to pdfmerger.io. Click the "Select Files" button or drag and drop your PDFs onto the upload area. A file picker will open, allowing you to select multiple PDFs at once. Once selected, all files will appear as thumbnails in a scrollable list on the screen.
Click and drag the edge of each thumbnail to reorder them visually. You will see a live preview of the final merge order. Once satisfied, click the green "Merge" button. The browser will process the files in seconds, and a download button will appear. Click it to save the merged PDF to your Downloads folder.
Browser-Based vs Preview: The Tradeoffs
Preview is built-in and requires no internet connection. If you merge PDFs frequently and need to work offline, Preview is the right choice. However, Preview's interface is not designed for bulk merging, and managing multiple windows is inefficient. Browser-based tools like pdfmerger.io are better for anyone merging more than three PDFs at once, especially if those PDFs live in different folders or cloud services. You do not need to copy files to a working folder first; the browser can gather them from anywhere.
Browser-based tools also offer one-click merging, instant visual reordering, and optional compression or rotation before saving. If privacy is a concern, pdfmerger.io is also browser-based, meaning your files never leave your Mac.
Frequently Asked Questions
Does macOS have a free PDF merger?
Yes. Preview, included with every Mac, can merge PDFs at no cost. However, the workflow involves multiple windows and manual dragging, making it slower than browser-based tools for large batches.
Is Preview as good as third-party tools?
For basic merging, yes. Preview can combine PDFs in any order and save the result. However, Preview lacks features like compression, rotation, or page extraction. If you only need to merge, Preview is sufficient. If you also need to compress, rotate, or split PDFs, a dedicated tool is faster.
Can I merge PDFs on a Mac without internet?
Yes, using Preview. Since Preview is a built-in app, you do not need internet to merge PDFs. If you prefer a browser-based tool, you will need internet to reach pdfmerger.io, but once the page loads, the actual merging happens locally and does not require a continued connection.
PDF Tools for Mac
- Compress PDF — Reduce file size before sharing.
- Split PDF — Extract individual pages or page ranges.
- Rotate PDF — Fix page orientation.