Merge PDF

Merge PDF Files in Your Browser

Merging is the least glamorous PDF job and the one people get wrong most often, almost always because the pages came out in the wrong order. This page explains how the ordering controls here work, what the merge copies across, and the two situations where it will stop and tell you it cannot proceed.

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 is 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 rather than trusting it. Files named with zero padding — page02.pdf, page10.pdf — sort the way you 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 rather than append 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 are not re-encoded, so a merge never costs you visual quality.

Two things are worth knowing about anyway:

• Interactive form fields keep their names. Two source files that both contain a field called name will behave as one field in the merged document — type into one and the other updates. Flatten the forms before merging if that matters.
• The output is often larger than you expect. Each source file brings its own embedded font subsets and colour profiles, and identical-looking fonts from different producers are not 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 cannot read a page tree it cannot decrypt, and guessing is not something a web page should do. 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 have queued at once.

When merging is not what you want

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

And if your goal is a single printable file from a folder of photos, skip this tool entirely — 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. Check the file list rather than 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 preserves it rather than normalising it, so a landscape scan stays landscape. Fix it afterwards with Rotate PDF.

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