PDF Merge

Combine multiple PDF files into one. Upload your PDFs, reorder them with the arrow buttons, then click Merge. Your files never leave your device — everything runs in the browser.

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Drop PDF files here or click to upload

Select multiple files at once — order them below

Understanding the PDF Merge

This tool combines two or more PDF files into a single document, entirely inside your web browser. It suits anyone assembling a contract from separate signed pages, joining scanned receipts for an expense report, or bundling chapters into one file. Add your PDFs, drag them into the order you want, and download one merged file. Because nothing is uploaded to a server, even confidential documents stay on your own device throughout.

How it works

The tool uses the open-source pdf-lib library running locally in JavaScript. Each file you add is read with the browser FileReader API into an ArrayBuffer, then loaded as a PDF document. A new empty document is created, and pages from every input are copied in your chosen sequence using copyPages and addPage, preserving the original page content and dimensions. The combined document is serialized back to bytes, wrapped in a Blob, and offered as a download. No file ever leaves your computer, so there is no upload wait and no privacy exposure.

Worked example

Imagine you have invoice-jan.pdf (2 pages), invoice-feb.pdf (3 pages), and a cover.pdf (1 page). Drag cover.pdf to the top, then the two invoices, and merge. The result is a single 6-page PDF whose pages appear in exactly that order: cover, then January's 2 pages, then February's 3. The output keeps each page's original size and orientation, and downloads as merged.pdf in a second or two with no upload step.

Tips & common mistakes

Reorder files before merging; the final page sequence follows the on-screen order top to bottom.
Add at least two files; a single PDF has nothing to combine.
Encrypted or password-protected PDFs may fail to load, so remove protection first.
Page sizes are preserved, so mixing A4 and Letter sources yields a document with mixed page sizes.
To merge only specific pages from a file, split those pages out first with the PDF Split tool, then merge the resulting PDFs here.
Very large files use browser memory, so close other heavy tabs if a huge merge feels slow.

How to Merge PDFs

1Click the upload area or drag-and-drop your PDF files. You can select multiple files at once.
2Use the ↑ / ↓ arrows to arrange the files in the order you want them in the final PDF.
3Click Merge PDFs. The merged file downloads automatically.

Frequently Asked Questions

Is my PDF uploaded to your servers?

No — all processing happens entirely in your browser using a JavaScript PDF library. Your files never leave your device. This also means it works offline once the page is loaded.

How many PDFs can I merge at once?

There is no strict limit set by us, but very large files may be slow depending on your device's memory. For best performance, merge fewer large files at a time.

Can I merge encrypted or password-protected PDFs?

Encrypted PDFs cannot be merged without first removing the password. Please decrypt them first using your PDF viewer before uploading.

Can I reorder the PDFs before merging?

Yes — use the ↑ and ↓ arrows next to each file to change the order. The merged PDF will follow the order shown in the list.

What browsers are supported?

Any modern browser: Chrome, Firefox, Safari, Edge. The tool uses the pdf-lib JavaScript library which is well-supported across all platforms.