Combining documents without uploading them
Merging PDFs is one of the most common office tasks and one of the most commonly outsourced to a website. That is worth pausing on, because the documents people merge — contracts, invoices, medical records, scanned identification, tax paperwork — are frequently the most sensitive files they own, and the standard approach involves uploading all of them to a server belonging to someone they have never heard of.
This tool does the merge in your browser. The PDF library runs as JavaScript on your machine, reads the files you select directly from disk, assembles the combined document in memory, and hands it back to you as a download. Nothing is transmitted at any point.
Order matters
Pages appear in the merged file in the order the source documents are listed, so set that order before merging. Use the arrows beside each row to move files up or down, and the cross to remove one you added by mistake. Files selected together are added in the order your operating system returns them, which is not always alphabetical.
What is preserved
Page content, embedded fonts, images and vector graphics all carry across intact, and each page keeps its own size and orientation. A merged document can therefore legitimately mix A4 portrait pages with landscape scans, which is normal when combining material from different sources.
Some document-level features do not survive a merge. Form fields, digital signatures, bookmarks and document-level JavaScript are generally lost, because they belong to the original file rather than to individual pages. A digital signature in particular becomes invalid once pages are extracted, which is by design — the signature attests to the original document, not to a new one built from parts of it.
Encrypted files
PDFs protected with a password cannot be read without it. If a file fails to merge, encryption is the most likely reason. Open it in a PDF reader, enter the password, and save an unprotected copy before merging.
Practical limits
Because the whole operation happens in memory, the constraint is your device's available RAM rather than any server-side upload cap. Ordinary documents of a few hundred pages merge in a second or two. Very large scanned files running to hundreds of megabytes may take longer and will use significant memory while processing.
Common uses
Assembling a single application pack from separate certificates and identification scans. Combining monthly invoices into an annual file for accounting. Putting a report body together with its appendices before circulating it. Consolidating scanned pages that a scanner saved individually.
Frequently Asked Questions
Are my PDF files uploaded to a server?
No. The merge happens entirely in your browser using a JavaScript PDF library. Your documents never leave your device.
How do I control the page order?
Use the up and down arrows beside each file in the list. Documents are merged in the order shown.
Why does my file fail to merge?
Almost always password protection. Open the file in a PDF reader, unlock it, and save an unprotected copy first.
Do form fields and signatures survive?
Generally no. Those are document-level features, and a digital signature necessarily becomes invalid when pages are combined into a new document.
Is there a file size limit?
There is no imposed limit. The practical constraint is your device's memory, since the whole document is assembled locally.