All processing happens in your browser. PDFs are never uploaded.
This merger concatenates multiple PDFs into one file using pdf-lib, entirely in your browser — the documents never leave your machine, which matters more for PDFs than most file types since they tend to be contracts, statements, and IDs.
What survives a merge and what quietly doesn't
Merging copies page objects: page content, embedded fonts, images, and page-level annotations all carry over, and page counts add exactly — a 2-page file plus a 3-page file yields 5 pages. What does not carry over is anything stored at the document level rather than on pages: the bookmark outline, named destinations, document metadata, and crucially the AcroForm dictionary that makes form fields interactive. If you merge fillable forms, expect the fields to lose interactivity or misbehave in the output. Fill and flatten forms before merging, or keep forms out of merges entirely.
When the merge fails
Password-protected PDFs are the most common failure: pdf-lib refuses to load encrypted files, and since the whole merge runs as one operation, a single locked file fails the batch with a generic error. Remove files one at a time to find the culprit, then decrypt it (opening and re-saving with the password in any PDF reader works) before retrying. The other practical limit is memory — every file is held in RAM as a raw byte buffer, so merging dozens of large scanned documents can exhaust a browser tab. Merge in batches of a few files, then merge the intermediates.
Step by step
- Add two or more PDFs — multi-select in the picker or drop them in batches; new files append to the list.
- Arrange the order with the Up and Down buttons on each row; Remove drops a file without clearing the rest.
- Merge. Pages are copied in list order and the result downloads immediately as merged.pdf.
One thing people ask
Can I merge specific pages rather than whole documents?
Not here — this tool copies every page of every file. If you need a page range, split the PDF first in another tool, then merge the pieces. Ordering whole files is the only arrangement control offered.
The pdf-to-base64 converter turns the merged output into an embeddable string, and base64-to-pdf reverses it.