How to merge PDF files online
Merging PDFs used to mean installing desktop software or sending your documents to a remote server you know nothing about. PDF Toolkit changes that. The merge tool runs entirely in your web browser — your files are read locally using the browser's File API and processed by pdf-lib, a JavaScript library that never makes a network request with your file data.
Step by step
- Add your files — drag and drop multiple PDFs onto the zone above, or click to browse. Each file appears as a card.
- Reorder if needed — drag the handle (⠿) on any card to rearrange files into the order you want. Use arrow keys for keyboard access.
- Click Merge files — processing runs in a background thread so your browser stays responsive.
- Download — save the merged file directly to your device. No email link, no expiry, no server round trip.
Why client-side processing matters for privacy
Most online PDF tools upload your files to cloud servers, process them there, and let you download the result. That means a third party holds a copy of your document — even briefly. For contracts, financial statements, or any document with personal information, that is a real risk. PDF Toolkit eliminates it: there is no server configured to receive your files.