Merge PDF Files

Features

• Merge any number of PDFs in the order you selected them, with the list shown for checking
• Optionally take only certain pages from each file (written as 1-3,5)
• Rename the output (merged.pdf by default)
• Owner-password PDFs (print/edit restricted) can be merged too
• Up to 100 MB per file and 30 files at a time
• Reports total pages, source file count and the resulting size
• Nothing is uploaded and no server is involved — it works offline

How to use

1. Drop several PDFs in (or click to choose, holding Ctrl / ⌘ for each)
2. Check the order in the list — that is the merged order
3. Optionally set a page range or an output file name
4. Download the merged file

FAQ

How is the merged order decided?

Purely by the order you chose the files: the order you dropped them, or the order you clicked them. The tool does not sort by file name or modification time — that looks clever, but a wrong sort (chapter 3 behind chapter 10) is almost impossible to spot. The page therefore lists your selection in order; glance at it before merging (use Clear and choose again if the order is wrong).

Can encrypted PDFs be merged?

Two cases. Files with an owner password (they open fine but restrict printing, copying or editing) can be — those open in any browser, so treating them as unreadable would be surprising. Files with a user password (you cannot even open them) cannot be; the bytes come out as noise and the tool says "needs the open password". Open those in a reader, enter the password, save a copy, and merge that.

Why is the merged file smaller (or larger) than the two originals together?

Larger when fonts and images are kept per document — three differently typeset PDFs carry three font sets. Smaller when the documents share resources (the same font subset from one scanner, the same blank template), which get merged and deduplicated. To genuinely shrink a scan, rebuild it with the images-to-PDF tool or use your reader's "reduce file size" feature.

Are the files uploaded?

No. Merging runs through pdf-lib in the browser's memory with no network requests at all, and it keeps working offline. Contracts, invoices and ID scans are exactly the documents that should not be handed to a third-party server — that is the reason this tool exists.