Merge PDF
Drop two or more PDFs in the order you want them combined. The merge runs entirely in your browser — files never leave your device — and you get a single combined PDF back.
Why merge PDFs?
- Combining a contract, signed signature page, and supporting exhibits into a single document for a closing packet.
- Stitching a receipt, expense form, and approval email (each saved as PDF) into one expense submission.
- Joining multi-day scanned invoices into a single monthly archive PDF for accounting.
- Bundling a manuscript, cover letter, and bibliography into one combined submission PDF.
- Pulling a half-dozen scanned pages of a passport, visa, and travel docs into a single immigration submission.
- Assembling a chapter draft, reviewer notes, and figure plates into a single review-ready PDF.
How it works
Each PDF you drop is loaded with pdf-lib's PDFDocument.load (with ignoreEncryption set, so PDFs locked only by owner restrictions still merge). All page indices from each source are copied via copyPages into a fresh destination document, in the order the files were added. The destination is saved as a new PDF and downloaded directly. Nothing uploads — pdf-lib runs as JavaScript on this page, and your files stay on your device.
Frequently asked questions
Can I reorder files before merging?
Drop them in the order you want. To remove a file mid-list, click the × next to it and re-add the rest in the right order. A drag-to-reorder UI is on the roadmap.
Will bookmarks, links, and form fields be preserved?
Page content, embedded fonts, and images come through cleanly. Cross-document links and bookmarks may not survive — pdf-lib doesn't currently rewrite navigation references across copied documents. Acrobat is more thorough on this if you need a perfect bookmark tree.
Will encrypted PDFs work?
PDFs with owner-only restrictions (printing, copying, etc.) merge fine. PDFs that need a password to open won't merge until you unlock them — use the unlock-pdf tool first if you have the password.
Is there a file count or size limit?
No hard limit, but everything happens in browser memory. Combining ten 5 MB PDFs is instant; combining a hundred 50 MB PDFs may run your tab out of RAM. For massive merges, a desktop tool (qpdf, Acrobat) is faster.
Are my files uploaded?
No. All processing happens in this page's JavaScript. Even sensitive merges — contracts, medical records, tax docs — never leave your device.
About this tool
Merging PDFs is the most common operation in any PDF toolkit — every signed contract, expense report, and submission packet starts with several files that need to become one. The mechanics are well-understood: lift each source's pages, append them in order, write a new document. The catch is that this used to mean uploading sensitive documents to a third-party site (Smallpdf, ILovePDF, PDF24) just to combine them — which is a privacy problem when the documents are NDAs, medical records, or tax returns. Doing the merge client-side via pdf-lib keeps everything on your device and removes the upload-trust step entirely.