Merge PDF files online — free & private
Combine multiple PDFs into one document. Drag the files to reorder them, preview the order, and download the merged file — all processed in your browser. Nothing uploaded, nothing stored.
2 PDFs · 0 pages
How to merge PDF files online
Combining PDFs with PDFluna takes under a minute and runs entirely in your browser. There is nothing to install, no account to create, and your files never leave your device. Here is the full process:
- Upload your PDFs. Drag and drop two or more PDFs onto the upload area, or click Choose PDFs to pick them from your device. You can add more files at any time — the list keeps growing until you merge.
- Reorder the files. Drag a file card up or down to change its position in the final document. On mobile, use the ↑ and ↓ buttons on each card. The numbered badges show the final order at a glance.
- Remove any files you don’t want. Click the ✕ on a card to drop it from the queue. Encrypted or corrupted files are flagged automatically and skipped from the merge.
- Merge your PDFs. Click Merge PDFs to combine them into a single file. Processing runs in your browser — we never upload a byte. Typical 5-file merge finishes in under three seconds.
- Download the combined PDF. Your merged file downloads automatically. Text layers, images, and signatures from every source PDF are preserved exactly — no re-encoding.
When you need to merge PDF files
People reach for a PDF merger for the same reasons every day: a single file is easier to send, easier to file, and easier to sign than a stack of loose documents. These are the jobs-to-be-done we see most often:
- Combining a scanned contract with its signed amendment and the corresponding invoice into a single handoff to a client
- Consolidating expense receipts for a reimbursement claim — one PDF instead of twelve attachments
- Assembling chapter drafts, images, and reference material into a complete manuscript
- Packaging a tender response: cover letter + company brochure + pricing sheet + reference list as one file
- Merging multi-part reports that arrived from different teams over several emails
- Building a portfolio PDF from individual work samples, case studies, and certificates
If the merged file is bigger than you expected, you can compress the merged file to cut its size for email. If you need the opposite — breaking one PDF back into separate files — use split a PDF into individual files instead.
How PDFluna merges your PDFs
Most online PDF mergers upload your files to a server, combine them there, and send back the result. That round trip is slow on big files, raises obvious privacy questions with contracts and ID documents, and often degrades images because the server re-encodes them on the way back.
PDFluna does none of that. When you drop files onto the page they are read into memory with the browser's File API, validated individually (size, magic bytes, encryption), and then combined in-place using pdf-lib. Pages are copied verbatim from each source into the output via copyPages — no re-encoding, no recompression, no watermark. Text layers, images, embedded fonts, and signatures are preserved exactly as they appear in the originals. The final file lands on your device as a direct browser download. You can verify the privacy claim with your own eyes: open DevTools, switch to the Network tab, and run a merge. You will see zero requests during processing.
The merge is fast because modern browsers are fast — a typical five-file merge totalling 20 MB finishes in under three seconds on a mid-range laptop. If you picked up unwanted pages in the process, remove pages from the merged PDF afterwards, or rotate pages that face the wrong way before you send it. All of our tools use the same zero-upload, browser-only architecture.
Frequently asked questions
How many PDFs can I merge at once?
Up to 50 PDFs per merge, with a soft warning appearing once you pass 20 files. Each individual PDF can be up to 100 MB. There is no hard limit on the merged output size, but we warn before downloading if the combined file will exceed 500 MB.
Can I rearrange the PDFs before merging?
Yes. Drag the file cards up or down to reorder them on desktop. On mobile, each card has ↑ and ↓ buttons. The numbered badges on the left of each card always show the final position, so you can double-check the order before you merge.
Is there a file size limit?
Each individual PDF must be under 100 MB. The merged output has no hard limit, but very large merges (500 MB+) can take a minute and stress low-RAM devices. For big combines we recommend compressing the result afterwards with our Compress PDF tool.
Will the merged PDF keep bookmarks and form fields?
Form fields are preserved from each source PDF. Be aware that if two PDFs both contain a field named "signature" the names will collide in the output, and only one will be reachable by name — flatten forms first if that matters. Bookmarks (document outline) are stripped in the current version; this is a pdf-lib limitation we plan to address in a future release.
Is my file uploaded to your server?
No. All merging happens in your browser using JavaScript (pdf-lib). You can verify this yourself: open DevTools → Network before merging — you will see zero requests while the merge runs. Your files never leave your device.
Does this work on mobile?
Yes. The tool is fully responsive. File cards stack vertically, reordering switches from drag-and-drop to ↑ / ↓ buttons (HTML5 drag-and-drop is unreliable on touch), and the merge button sticks to the bottom of the screen so you can always reach it while scrolling the file list.
Can I merge password-protected PDFs?
Not directly. Encrypted PDFs are flagged with an error on their file card and are excluded from the merge. Unlock them first with our Unlock PDF tool, then come back here to merge them with the others.
What if my PDFs have different page sizes or orientations?
Each page keeps its original size and orientation in the merged PDF — so you may end up with A4 portrait pages followed by Letter landscape pages. That is correct behaviour: we never resize or re-orient your source content. If you want a uniform orientation, rotate the odd pages first with our Rotate PDF tool before merging.