Merge PDF

Combine multiple PDF files into one document — your files never leave your device.

ToolFlux's Merge PDF tool combines as many PDF files as you like into one document entirely in your browser — your files never upload, and you can drag to set the exact page order before saving.

Your files never leave your device — all merging happens in your browser.

      Merge PDF files online — free and private

      Combining several PDFs into a single file should be simple, and it should not require uploading your private documents to a stranger’s server. This Merge PDF tool joins as many PDF files as you like into one tidy document — contracts, invoices, scanned receipts, lecture notes, or chapters of a report — and it does the entire job inside your own browser. Nothing is uploaded, nothing is stored, and nothing is shared. When you close the tab, the files are gone from memory.

      How to merge PDF files

      1. Add your PDFs Drag and drop two or more PDF files onto the box above, or click it to browse. Only PDF files are accepted; anything else is ignored with a clear message.
      2. Put them in order Each file appears in a numbered list. Drag an item up or down — or use the arrow buttons — until the order matches the final document you want.
      3. Click “Merge PDFs” A progress bar shows the tool working through your files. Larger documents take a moment because everything is processed locally.
      4. Download the result When merging finishes, a download button appears for merged.pdf. Save it wherever you like.

      Popular ways people use this tool

      • Bundling paperwork. Combine a cover letter, résumé, and references into one application file.
      • Accounting and expenses. Stitch monthly invoices or scanned receipts into a single document for bookkeeping.
      • Study material. Merge separate chapter PDFs into one file you can read and annotate in order.
      • Legal and admin. Assemble signed contracts, addenda, and exhibits into a single packet without exposing them to a cloud service.
      • Scanned pages. Many scanners save each page as its own PDF — merge them back into one readable document.

      Why merge PDFs in your browser?

      Traditional “merge PDF” websites upload your files, process them on a remote server, and ask you to trust that they delete them afterwards. For anything sensitive — financial records, identity documents, NDAs — that is a real privacy risk. Because this tool runs 100% on your device using the open-source pdf-lib engine, your documents are never transmitted over the internet. It also means the tool works offline once the page has loaded, and there are no file-size caps imposed by an upload limit. The only thing the server ever sends you is the web page itself.

      Quality is preserved end to end. Pages are copied directly into the new document, so selectable text remains selectable, fonts stay embedded, and images keep their original resolution. The tool simply concatenates the pages in the order you choose — it does not recompress or flatten them — so the merged file looks exactly like the originals stacked together.

      Frequently asked questions

      Are my PDF files uploaded to a server?
      No. Merging happens entirely inside your web browser using JavaScript. Your files never leave your device and are never sent anywhere, which keeps confidential documents private.
      Is there a limit on how many PDFs I can merge?
      There is no fixed file-count limit. Because the work runs on your own machine, the practical limit is your device’s available memory. Merging a handful of typical documents is instant; very large scanned PDFs use more memory.
      Can I change the order of the files before merging?
      Yes. After you add files, drag any item in the list — or use the up and down buttons — to set the exact order. The merged PDF follows the order shown in the list, from top to bottom.
      Does merging reduce the quality of my PDFs?
      No. Pages are copied as-is into the new document, so text stays selectable and images keep their original resolution. Merging only combines pages; it does not recompress them.
      Why did I get an error about an invalid or password-protected PDF?
      The tool checks each file’s header and structure before merging. If a file is not a real PDF, is corrupt, or is encrypted with a password, merging stops with a message so you can fix it. Remove the password (or the bad file) and try again.
      Does the merge tool work offline?
      Yes. Once the page has loaded, everything it needs is already on your device, so you can disconnect from the internet and keep merging. The only thing the server ever sends you is the web page itself.
      Can I merge PDFs on my phone?
      Yes. The tool runs in any modern mobile browser. Pick your PDFs from your phone’s files, reorder them with the arrow buttons, tap Merge PDFs, and the combined document downloads to your device.