Select multiple PDFs and combine them into one document. Drag to reorder.
Drop your PDFs here
or click to select
Choose filesPDF only · Multiple files accepted
≡ Drag files to change order
FusionPDF's PDF merger lets you combine multiple PDF documents into a single file in seconds — directly in your browser. Whether you need to merge 2 files or 20, the process is the same: drag your files in, arrange them, and download the result.
Your files never leave your device. Unlike most online PDF tools, FusionPDF uses PDF-lib, a JavaScript library that processes everything locally. No file is ever sent to a server. This means your documents stay 100% private.
FusionPDF's merge tool is completely free, requires no account, and works on any device — desktop, tablet or smartphone.
Drag & drop your PDF files onto the upload area above, or click to browse. Add as many files as you need — there is no limit.
Drag the files in the list to arrange them in the order you want. The final PDF will follow this order exactly.
Click "Merge & Download". Your browser combines the files instantly and the merged PDF downloads automatically.
FusionPDF's PDF merger lets you combine multiple PDF files into a single document directly in your browser — no upload, no account, no file size limit. Drag and drop your files, reorder them as needed, and download the merged PDF in seconds. Everything runs locally on your device, so your files stay completely private.
Your files never leave your device. FusionPDF uses pdf-lib, a JavaScript library that runs entirely in the browser. No file is ever sent to a server. This means your documents stay 100% private, regardless of what they contain.
Drop two or more PDF files onto the upload area or click to select them from your device. Once loaded, drag the file cards to reorder them in the sequence you want. Click Merge and Download — your combined PDF downloads instantly. You can merge as many files as needed in a single operation.
Merging PDFs is useful when you need to combine chapters of a report, assemble scanned pages of a contract, bundle invoices for accounting, consolidate presentation slides, or group related documents before sharing with a client. It eliminates the need to send multiple attachments and keeps everything in one organized file.
There is no software limit built into the tool. You can add as many PDF files as you need in a single merge operation. The practical limit is your device's available RAM. A machine with 8 GB of RAM handles dozens of large PDFs without issue — most routine merges of 5-20 files complete in a few seconds regardless of device.
If you're merging very large files and the browser tab becomes slow, try splitting the job into two smaller merges, then merging the two results. Page quality is preserved exactly either way — pdf-lib copies pages without re-encoding, so there is no generational quality loss from multiple merge passes.
Merge combines multiple PDFs in sequence: all pages of file 1, then all pages of file 2, and so on. Use this when assembling separate chapters, reports, or standalone documents into one file.
Interleave alternates pages from two PDFs: page 1 from file A, page 1 from file B, page 2 from file A, page 2 from file B. This is the right operation when you've scanned a double-sided document as two separate single-sided passes — odd pages in one file, even pages in the other. Use the Interleave tool for this case.
Insert adds specific pages from one PDF into another at a precise position. For example, inserting pages 3-5 of a new contract version at position 7 of the original. The Reorder Pages tool handles this kind of targeted page-level editing.
Not directly. Password-protected PDFs cannot be read by pdf-lib until they are unlocked. Attempting to merge a locked file will result in an error. The solution is straightforward: use the Unlock PDF tool to remove the password first, then add the unlocked file to your merge operation.
If you don't know the password, the file cannot be unlocked. This is by design — the encryption is there to prevent exactly that. Contact the file's original sender for an unlocked copy.
A merged document often combines multiple sensitive sources. A typical scenario: a signed contract, a copy of a government-issued ID, and a bank statement — merged into a single onboarding package for a financial institution. Each of those source files contains information you'd never want sitting on a stranger's server.
Most online PDF mergers upload all your files to a cloud server, process them there, and return a result. Some claim to delete files after a set period. But "deleted" on a server is not the same as never uploaded in the first place. With FusionPDF, the merge happens entirely in your browser. Your files are never transmitted, so there's nothing to delete.
For a deeper look at how browser-based PDF tools work and how to verify that no upload is happening, read our complete guide to merging PDFs for free.