How do I combine two PDF files?

Add both PDF files using the file picker or drag and drop, use the arrows to set the order, then click Merge. The combined PDF downloads automatically.

What is the combined file called?

It downloads as merged.pdf, with every page of the first file in the list followed by every page of the second. The Merge button becomes active once two PDFs are in the list.

Is there a file size limit?

All the PDFs you add can total up to 100 MB. Files that would go over that are rejected with a clear error before any processing starts.

Can I reorder the two PDFs before merging?

Yes. Use the up and down arrow buttons on each file row to set the order before you click Merge.

What happens to the original files?

Your original files are left unchanged on your device. The tool only downloads a new, combined PDF.

Combine Two PDF Files

Add two PDF files, arrange them in the order you want, and download the merged result. All processing happens in your browser.

Drop PDF files here or click to browse

You can add multiple files

How it works

Both PDFs are loaded into memory and parsed with pdf-lib. The tool copies every page of the first document into a fresh target document, followed by every page from the second, in the order you chose. The combined PDF is serialised in your browser and downloaded straight to your device.

Processing runs in your browser

All merging happens inside your browser tab. pdf-lib combines your PDFs entirely in memory; our servers are not involved at any point. You can confirm this yourself in your browser's DevTools Network tab.

Related operations

For pulling out a single section before merging, try split PDF. To straighten sideways scans first, use rotate PDF. For shrinking the combined file, see compress PDF.

Frequently asked questions

How do I combine two PDF files?: Add both PDF files using the file picker or drag and drop, use the arrows to set the order, then click Merge. The combined PDF downloads automatically.
What is the combined file called?: It downloads as merged.pdf, with every page of the first file in the list followed by every page of the second. The Merge button becomes active once two PDFs are in the list.
Is there a file size limit?: All the PDFs you add can total up to 100 MB. Files that would go over that are rejected with a clear error before any processing starts.
Can I reorder the two PDFs before merging?: Yes. Use the up and down arrow buttons on each file row to set the order before you click Merge.
What happens to the original files?: Your original files are left unchanged on your device. The tool only downloads a new, combined PDF.

Last reviewed September 30, 2026

Other pages for this tool

Related tools

Background reading: Complete guide to PDF tools