The easiest way to merge PDFs privately
Most "merge PDF" websites upload your file to a remote server, merge it there, then hand back a download link. For a concert ticket this is fine; for a signed lease or a medical record, it's a privacy exposure you can avoid. This page uses pdf-lib, a JavaScript PDF engine, to do the whole merge inside your browser tab. The file bytes never leave your device.
Drop files in any order, use the up/down controls to arrange them, set an output filename, and click Merge. The tool streams each source document's pages into a new PDF and saves it as a blob. Everything that happens after the page loads works offline.
What's preserved in the merged PDF?
- Text and images — exactly as they appear in each source.
- Links and bookmarks — internal and external links pass through.
- Form fields — preserved, though field names may collide; rename if that matters.
- Fonts — embedded fonts carry across, so no "missing glyph" boxes.
What's not
Digital signatures become invalid after a merge because the document bytes change. If signatures matter, sign the output PDF instead of the inputs. Permissions and passwords on protected PDFs are also stripped in the merged file — you can't merge into a file that someone else owns.
Frequently asked
Are my PDFs uploaded anywhere?
No. The PDF engine runs as JavaScript inside your browser tab. The file bytes are read, copied into a new PDF, and handed back to you as a download — all client-side.
Is there a file size or page count limit?
Not hard-coded, but browsers limit how much memory a tab can use. Practically, this handles PDFs totaling a few hundred MB with no issue on a modern laptop. Very large scans (hundreds of pages at 300 DPI) may be slow.
Can I merge password-protected PDFs?
Only if the PDF has no "open" password. Encrypted PDFs will fail to load. Remove the password in Preview / Acrobat first, then merge.
Why is the output PDF bigger than the sum of the inputs?
pdf-lib writes a fresh PDF and can't dedupe fonts or images across source files. If the same 2 MB image appears in five PDFs, it'll appear five times in the output.
Can I also split PDFs here?
Not yet. Split, reorder-pages, and password-remove tools are on the roadmap. Let us know which would help most.