Merge PDF Files

Combining several PDFs into one is one of the most common document tasks — attaching contracts, assembling a portfolio, or stitching receipts before emailing accounting. This guide shows how to merge PDF files locally in your browser using the Merge PDF tool, with no upload and no account.

TL;DR

Open the Merge PDF tool, add two or more PDF files, drag them into the order you want, and download a single merged PDF. Everything runs in your browser — your documents never leave your device.

How local merging works

When you add PDF files to the tool, each file is read into your browser’s memory as an ArrayBuffer. The pdf-lib library — loaded only on this tool’s page — copies the pages from each source document into a new combined PDFDocument. Once all pages are assembled, the result is serialized back to a single PDF file and offered as a download.

Because the entire process happens in the browser’s JavaScript runtime, your files are not transmitted to any server. The tool works offline after the page has loaded.

Step-by-step

1. Open the Merge PDF tool at /en/tools/pdf/merge-pdf/.
2. Add your PDF files. Use the file picker to select two or more .pdf files. You can add more files later if you forgot one.
3. Reorder the files. Drag each file into the order you want them to appear in the merged document. The first file in the list becomes the first pages of the output.
4. Merge. Trigger the merge action. The tool reads every file, copies its pages in order, and assembles one document.
5. Download. Save the merged PDF. The output filename is based on the first file’s name.

Limits to know

• Only PDF input is supported. Images, Word documents, and other formats cannot be added directly — convert them to PDF first (see the image-to-pdf tool for photos).
• Encrypted or password-protected PDFs may fail. If a source PDF cannot be parsed, the tool reports that the file may be corrupt or use a format the parser cannot read.
• Large files process on your device. Merging many large PDFs takes time proportional to the total page count and uses your available memory. Very large merges may be slow on low-memory devices.
• No page-level editing. This tool joins whole files. To delete specific pages, use the Remove PDF Pages tool after merging.

When to merge vs. split

Merging is right when you have several complete documents that should travel together — a signed contract plus its appendix, or a semester’s worth of assignment PDFs. If you instead need to extract or delete pages from one document, use Remove PDF Pages. And if the merged result is too large to email, follow it with Reduce PDF File Size.

FAQ

Can I merge more than two PDFs?

Yes. Add as many PDF files as you need and drag them into order. The tool processes them sequentially into one output document.

Is it safe to merge confidential PDFs here?

The files are processed entirely in your browser and are not uploaded to a server. As with any browser tool, use your judgment for highly sensitive documents and close the tab when finished.

Why did one of my PDFs fail to merge?

The most common cause is an encrypted or password-protected PDF that the parser cannot read without the password. Corrupt or unusually structured files can also fail. Try re-saving the source PDF from its original application, then merge again.

Can I reorder pages within a single PDF?

This tool reorders whole files, not individual pages inside one file. To rearrange pages within a document, split it with Remove PDF Pages first, then merge the pieces in the new order.