Merge PDF

Merge PDF Files in Your Browser

Merging is the least glamorous PDF job and the one people get wrong most often, nearly always because the pages came out in the wrong order. Below is how the ordering controls work, what the merge copies across, and the two situations where it will stop and tell you it can't go on.

Getting the order right before you merge

Add two or more PDFs and each one appears as a row in a list. Every row has Up and Down buttons that move that file one position. There's also a Sort A-Z button that reorders the whole list by filename.

Sort A-Z is genuinely useful, but be careful with numbered scans. Filenames sort as text, so page10.pdf lands before page2.pdf. If your files came off a scanner or a camera, check the list after sorting instead of trusting it. Files named with zero padding, like page02.pdf and page10.pdf, sort the way you'd expect.

There are no page thumbnails and no drag-and-drop. The list shows filenames and page counts, and you move rows with the buttons. If you need to interleave pages from two documents instead of appending one after the other, merge them first and then retype the sequence in Organize PDF.

What gets copied, and what quietly changes

Page content is copied as-is. Text stays selectable, vector art stays vector, and scanned images aren't re-encoded, so a merge never costs you visual quality.

There are two things to watch for, though:

• Interactive form fields keep their names. If two source files both contain a field called name, they'll behave as one field in the merged document: type into one and the other updates. Flatten the forms before merging if that matters to you.
• The output is often larger than you'd expect. Each source file brings its own embedded font subsets and colour profiles, and fonts that look identical but come from different producers aren't the same object.

The result downloads as merged.pdf.

Encrypted inputs stop at the door

If any file you add is encrypted, the upload is refused with a message naming that file. The merge engine can't read a page tree it can't decrypt, and a web page shouldn't be guessing. Run the file through Unlock PDF first, then come back.

The size ceiling is 100 MB for any single file and 250 MB for everything you've queued at once.

When merging isn't what you want

If you only need three pages out of a 400-page report, don't merge the whole thing and delete pages afterwards. Pull the pages you want with Extract Pages first, then merge the small results. It's faster and the output is a fraction of the size.

And if you want a single printable file from a folder of photos, skip this tool. Image to PDF does that in one pass, without you making fifteen intermediate PDFs.

Troubleshooting a merge that looks wrong

The page order is scrambled. Start by checking the file list, not the output. Almost every reported ordering bug turns out to be Sort A-Z applied to unpadded numeric filenames.

A page appears sideways. Rotation is a per-page property that travels with the page. The merge keeps it as it was instead of normalising it, so a landscape scan stays landscape. Fix it afterwards with Rotate PDF.

Bookmarks are gone. Outline entries aren't rebuilt across documents. If your workflow depends on a table of contents, build it in a desktop editor after merging.