How to merge PDF files online
- Upload your PDFs — Click "Choose PDF files" or drag and drop multiple PDFs into the upload area. You can add up to 20 files at once.
- Rearrange the order — Drag and drop the file cards to set the exact order pages will appear in the merged PDF.
- Name your file — Give your merged PDF a custom name before downloading.
- Merge and download — Click "Merge and download". Your combined PDF is generated instantly in your browser and downloaded automatically.
Why use desPDF to merge PDFs?
- 100% private — Your PDF files never leave your device. All merging is done locally in your browser using pdf-lib.
- Completely free — No subscription, no trial period, no hidden costs. Merge as many files as you need at no charge.
- No account needed — Start merging immediately with no sign-up, no email and no password.
- No watermark — The merged PDF is clean and professional with no branding added.
- Drag-and-drop reordering — Arrange files in any order before merging. Page thumbnails help you visualise the result.
- Up to 20 files — Merge up to 20 PDFs in a single operation with no page limit.
- Works on all devices — Desktop, tablet and smartphone, in any modern browser.
Common uses for PDF merging
- Freelancers & contractors — Combine a quote, purchase order and technical appendices into one PDF to send to a client.
- Students & teachers — Assemble multiple chapters, exercises and answer keys into a single complete document.
- Businesses — Consolidate monthly reports, supplier invoices or multi-page contracts into one organised file.
- Legal & administrative — Merge scanned documents, forms and supporting attachments for submissions.
Frequently asked questions
Are my PDF files uploaded to a server?
No. All processing is done entirely in your browser using pdf-lib, an open-source JavaScript library. Your PDF files never leave your device and are never transmitted to any server.
How many PDF files can I merge?
You can merge up to 20 files per operation, with no limit on the number of pages in each file.
Can I choose the order of pages before merging?
Yes. Before merging, drag and drop the file cards to set the order. The file order determines the page order in the final merged PDF.
Is there a watermark or logo on the merged PDF?
No. The merged PDF is completely clean — no watermark, no desPDF branding, no added text of any kind.
Does the tool work on mobile?
Yes. The PDF merger works on all modern devices including smartphones and tablets.