Can I reorder files before merging?

Yes. After uploading your PDFs, you can drag and drop them into any order before merging. The final PDF follows the order you set.

Is there a limit on the number of PDFs I can merge?

There is no hard limit. Since merging happens in your browser, performance depends on your device. Combining dozens of files typically works without issues.

Are my files uploaded to a server?

No. All processing happens locally in your browser using pdf-lib. Your files never leave your device.

Can I merge PDFs with different page sizes?

Yes. Each page keeps its original dimensions. If one PDF is A4 and another is Letter, both sizes appear in the merged output as-is.

Does merging preserve bookmarks and links?

Internal hyperlinks within each PDF are preserved. Bookmarks and cross-document links may not carry over, since the page structure changes during the merge.

Merge PDF online: free, no upload required

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How it works

Add your PDF files

Drop multiple PDFs onto the upload area. There is no limit on the number of files.

Reorder if needed

Drag files up or down to set the order they appear in the final document.

Merge and download

Click Merge and download your combined PDF. All files joined into one.

Frequently asked questions

PDF4.dev API

Generate PDFs programmatically

Create HTML templates with variables, then render pixel-perfect PDFs with one API call. Invoices, receipts, certificates: any document, any language.

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Merge PDF