Merge PDF
Files are merged in the order you add them. To change the order, just drag them in again in the order you want.
Drag in PDFs (multiple allowed), or Choose file
Merged in the order added · Processed locallyIf a PDF has an open password, pdf-lib cannot read it and it will be marked as failed in the list. Remove the password in the original software first.
When to use it
- A client or portal accepts only one PDF, and you need to submit a contract, its appendix, and a signed scan together.
- You photographed a multi-page document on your phone, or exported several files from different apps, and need them as one file for printing or email.
- The merged file came out in the wrong order and you need to swap two documents before merging again
When not to
- The files rely on bookmarks, outlines, form fields, or a digital signature — pdf-lib copies page content, not those structures.
- You only need a few pages out of one PDF, or want to delete pages — merging can't remove pages; split instead, or delete pages in the original first.
Merging runs entirely in the browser via pdf-lib; the PDFs are never uploaded and are cleared when you close the tab. There's no fixed page limit, but scans of several hundred MB can exhaust memory on a phone, encrypted files are skipped, and bookmarks, outlines, form fields, and digital signatures aren't carried over — only the page content is copied.
Frequently asked
Are my PDFs uploaded when merging?
No. pdf-lib assembles the pages inside your browser, so the files never reach a server. The first merge downloads a ~500 KB pdf-lib script, which is reused for the rest of the session.
Why was one PDF skipped?
Almost always because it has an open password: pdf-lib can't decrypt it, so the file is marked as failed and skipped while the others still merge. Save a password-free copy from the original app first. A .pdf that is corrupted or is really a renamed image will fail the same way.
Can I change the merge order?
Yes. Every row has ↑/↓ buttons and a × to remove it, and you can drag rows to reorder them. Top to bottom is the merge order. Merging needs at least two PDFs.