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Merge PDF Files

Merge multiple PDF files into one document for free. No upload, no signup — everything runs in your browser. Fast, private, and secure.

Merging PDFs is the fastest way to consolidate multi-part documents — job applications, monthly invoice bundles, multi-chapter proposals — into a single file that travels easily by email. OpenPDF runs the merge locally with pdf-lib, so source fidelity is preserved byte-for-byte and nothing is uploaded. You can combine unlimited files, reorder page-by-page before running, and the result opens in every PDF viewer without reflow.

How it works

  1. Add your PDFs. Drag and drop multiple PDF files onto OpenPDF or click to browse.
  2. Reorder pages. Drag thumbnails to arrange pages in the exact order you want in the final document.
  3. Merge locally. OpenPDF combines the files 100% in your browser using pdf-lib — nothing uploads.
  4. Download the merged PDF. Click Download to save the combined file to your device.

Common use cases

  • Combining a scanned cover letter, CV and references into one PDF for a job application.
  • Merging supplier invoices into a monthly bundle for bookkeeping.
  • Assembling a client-facing proposal from chapters exported from different design tools.
  • Stitching together bank statements spread across quarterly PDFs for a loan application.

Frequently asked questions

Is there a limit on how many PDFs I can merge?

No hard cap beyond browser memory. Very large merges (hundreds of files or a total of several hundred MB) may run slowly but still complete locally.

Does merging preserve bookmarks and annotations?

OpenPDF preserves the content of each page, including annotations embedded in the source files. Bookmark structures may not survive in all cases depending on how the source PDF was generated.

Can I reorder pages before merging?

Yes. After dropping your files, drag the thumbnails into the order you want before running the merge. The final PDF follows whatever order you set.

Is merging uploaded to a server?

No. pdf-lib combines the files in your browser. Nothing ever touches a server.

Why OpenPDF

OpenPDF is an independent project built around one principle: the PDFs you edit should never leave your device. Every tool — merge, split, sign, organize, annotate, compress, watermark, add page numbers — runs entirely in your browser using WebAssembly and modern JavaScript APIs. There is no upload step, no account, no email harvesting, and no premium tier gating the useful features. The codebase and the third-party scripts loaded for analytics and advertising are visible in the page source — Google AdSense and Google Analytics 4 load only after you accept cookies in the consent banner — so anyone can audit what is running before trusting the tool with sensitive contracts, scanned IDs, or financial documents.