Merge PDF Files Online – Combine PDFs Securely

What is PDF Merging?

PDF merging (also called PDF combining or joining) is the process of taking two or more separate PDF files and combining their pages into a single PDF document. metatool.in's free PDF merger accomplishes this entirely in your browser using the open-source pdf-lib library — no files are ever uploaded to any server.

Common use cases include: combining individual invoice pages into a single document before emailing accounting, merging research papers for archiving, assembling multi-chapter reports, or joining scanned documents into a single file.

How to Merge PDF Files

Click the upload area to select your PDF files (or use Ctrl+Click to select multiple). They appear in a sortable list below. Use the up/down arrows to reorder pages in the final document. When you're happy with the order, click Merge & Download PDFs — the combined file downloads instantly.

Key Benefits

100% Private: Files are never uploaded. Everything runs locally using the pdf-lib WebAssembly library.
No Watermarks: The merged output contains no metatool.in watermarks or added pages.
Unlimited Files: Add as many PDFs as your device's RAM allows.
Reorder Support: Control the exact page order using the up/down controls beside each file.

Frequently Asked Questions

No. metatool.in Merge PDF uses the open-source pdf-lib library that runs entirely in your browser. Your documents are never uploaded anywhere.

There is no limit on the number of files. The only constraint is your device's available RAM.

Yes. Use the up and down arrows beside each file in the list to reorder them before merging.

No. metatool.in never adds watermarks. The output PDF is clean and print-ready.

There is no hard limit. Very large PDFs (500MB+) may take a few seconds depending on your hardware, but they will be processed.

Related Free Tools

PDF Split — Extract pages from a PDF document securely.
PDF to Image — Convert PDF pages into high-quality JPG or PNG images.