You have three separate PDFs — maybe a contract, an appendix and a signed page — and you need to send them as one file. This is one of the most common PDF jobs there is, and you have several ways to do it.
Open a merge tool, drop your files in, and download the result. Because the work happens on your own machine, there is no upload wait and no privacy question to answer. The order of the merged document follows the order you added the files, so add them from first to last.
Practical tips before you start:
Both systems can combine PDFs using built-in tools. On macOS, open the first PDF in Preview, show the thumbnail sidebar, then drag the other PDFs into it and export. On Windows, you can print several documents to the "Microsoft Print to PDF" printer, one after another, but that loses bookmarks and can flatten form fields — acceptable for reading, not ideal for archiving.
If the receiving party needs to process each document separately — for example, a system that reads one invoice per file — merging will break their automation. Likewise, merging a fillable form with a scanned image can cause the form to render incorrectly on some viewers. When in doubt, send a ZIP archive instead.
Try it now: Merge PDF · Organize PDF