How merging works without a server
This tool uses pdf-lib, an open-source PDF library that runs as JavaScript in your browser. When you click merge, each document is parsed locally, its pages are copied into a new PDF in the order shown, and the combined file is assembled in your browser's memory and saved straight to your downloads. Open your browser's network panel while merging — nothing is transmitted.
Why that matters for sensitive documents
Server-based merge tools require you to upload the very documents people most often need to combine: leases, medical records, financial statements, legal filings. Even with good retention policies, that's an avoidable exposure. Local merging removes the question entirely, which also makes this tool safe to use under workplace policies that prohibit uploading client files to third-party sites.
Limits
The only limit is your device's memory; hundred-plus-page merges are routine on any modern laptop or phone. Password-protected PDFs need to be unlocked before merging. Page order follows the list order — use the arrows or drag to rearrange before you merge.