PDF Merge

About PDF Merge

PDF Merge joins several PDFs into a single document, in whatever order you put them, without uploading anything. Every online merger asks you to hand over the files first; this one does the work in the page you are already on, using pdf-lib to copy pages from each source document straight into a new one. That distinction is the whole point for the files people actually merge — signed contracts, scanned IDs, invoices for an expense claim, a thesis assembled from separately typeset chapters, a portfolio built from client work. Order is what usually goes wrong in a merge, so it is made explicit: files are listed in the order they will be joined, each row shows a thumbnail of its first page, and you move rows up and down until the sequence is right. Each file also takes an optional page range, which means you can drop a cover sheet or pull one appendix out of a long report without splitting it into a separate file first. The merged result is rebuilt live as you change any of that, page thumbnails and all, so you see the finished document before you download it.

Key features

• Runs entirely in your browser — the PDFs are parsed and rewritten locally and never uploaded
• Merge any number of files at once; drop them all in together or add more to the list later
• Explicit ordering — move any file up or down, or sort the whole list by filename (natural order, so "chapter-2" comes before "chapter-10")
• Per-file page ranges like "1-3, 7, 10-", so you can take part of a file without splitting it first
• First-page thumbnail on every row, so you are ordering documents you can recognise, not filenames
• Live page-by-page preview of the merged result, rebuilt whenever you reorder or change a range
• Page count, output size, and merge time shown as you go
• Keeps the original page content, size, and orientation — pages are copied, not re-rendered or re-compressed
• Handles mixed page sizes (A4 with US Letter, portrait with landscape) without stretching anything
• Files up to 100 MB each, limited only by your own machine
• Password-protected files are detected and reported rather than producing a broken output
• One click downloads the finished PDF; nothing is stored or logged anywhere

How to use it

1. Drop your PDFs onto the box, or click to choose them — you can select several at once.
2. Check the order in the list. Use the up and down arrows to move a file, or Sort by name to order the whole list at once.
3. Optionally type a page range next to any file — leave it blank to take the whole document.
4. Watch the merged preview on the right rebuild itself as you change the order or the ranges.
5. Click Download merged.pdf to save the combined file.

Tips & common mistakes

• Name your files with zero-padded numbers (01-cover.pdf, 02-intro.pdf) before merging. Sort by name then gives the exact order you want in one click.
• Merging is a copy, not a re-render: text stays selectable, links keep working, and nothing is re-compressed, so quality is identical to the sources.
• The output size is roughly the sum of the inputs. Merging does not compress — a 40 MB scan stays 40 MB inside the merged file.
• Use page ranges to drop repeated cover pages or signature sheets instead of splitting each file first. If you do need a standalone piece, use the PDF Splitter.
• Mixed page sizes are kept as they are. That is usually what you want for an appendix, but if you need one consistent size, normalise the sources before merging.
• A password-protected PDF cannot be merged — that restriction is the encryption doing its job. Remove the password in the app that made the file, then merge.
• Form fields and annotations copy across, but two files whose fields share a name can collide in the merged document. Flatten the forms first if the values matter.
• Merging does not rebuild the table of contents. Outline bookmarks from the source files are not carried into the combined document.
• Need to check what is inside a file before you merge it? Read it with the PDF Text Extractor.

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