Merging is the most common PDF task — combining a signed contract with its addenda, stitching invoices into a single month-end report, or chaining chapters into one book PDF before printing. The action sounds trivial, but doing it well means controlling page order across files and keeping the originals intact.
PDFly handles the merge entirely in your browser using pdf-lib. Files are read in memory, page order respects your drag arrangement, and the output is a clean PDF with the same fonts and images as the source documents. Nothing is uploaded — the input PDFs and the merged output never leave your computer.
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Step 1 — Open the Merge tool
Open the Merge tool. The upload screen titled "Merge PDF" lets you drop in any number of PDFs at once.
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Step 2 — Upload your PDFs
Click "Choose Files" and select two or more PDFs — or drag them straight onto the page. PDFly accepts as many files as you need; the page grid expands to show every page across every PDF.
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Step 3 — Reorder pages
After upload, your files appear as cards with color-coded badges (#1, #2, #3) and drag handles on the left. Drag any card to reorder the files; the merged output follows that order top-to-bottom. Switch to the Pages tab if you need to reorder individual pages across files.
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Step 4 — Merge and download
Set the output filename in the sidebar (the default is "merged.pdf"), then click "Merge PDFs". The combined PDF is built in your browser and the success panel shows the result — click the Download button to save it to your device.
Related guides
- Need to split instead? Split a PDF into separate filesThe opposite operation — pull a long PDF apart by ranges or split points.
- Pulling out specific pages? Extract pages from a PDFPick the pages you need from one PDF and save them as a single output file.
- Merged file too big? Compress the resultShrink the merged PDF for easier email or upload — the original quality stays.
