Are files uploaded to a server?

No. PDFs are read and merged entirely inside your browser using WebAssembly-capable APIs.

Why did a file fail to load?

Password-protected or corrupted PDFs may be rejected by the parser. Try unlocking or re-exporting the file first.

Is there a file size limit?

Very large files are limited by your browser memory. For huge archives, split work into smaller batches.

Merge PDF Files

Combine multiple PDF documents into one file in your browser. Reorder files, then download merged.pdf.

Add PDF files

Add two or more PDF files to merge.

About PDF merging

Each PDF is parsed locally with pdf-lib, pages are copied in order, and a new file is generated for download. Password-protected PDFs are not supported unless you unlock them first in another tool.

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Merge PDF Files in the Browser

How client-side PDF merging works and when it is the right fit.