Merge PDF
The Merge PDF tool combines several separate PDF files into a single document in your chosen order. It is handy when you need to turn multiple scanned pages, invoices, or chapters into one complete file for sending or printing. The entire merge runs directly in your browser — no PDF is uploaded anywhere and nothing leaves your device.
How merging PDF works
Merging PDF means the pages from several input documents are stacked one after another into a single new file. The tool creates an empty target document and, from each selected PDF in turn, copies all of its pages and appends them to the end. The input is two or more PDF files; the output is one new PDF containing their pages in the order in which you selected the files.
Complete pages are copied — including text, images, and vector graphics — so quality is never reduced: there is no conversion to an image and no recompression. The tool runs on the PDF-lib library as JavaScript in your browser; files are read locally into memory and never sent anywhere. The page order within each document is preserved; only the sequence of the documents relative to each other changes.
How to use Merge PDF
- Click the file picker and select two or more PDFs at once (hold Ctrl on Windows or Cmd on macOS, or select by dragging).
- Check the list of selected files shown below the picker — the files will be merged in this order.
- Click the Merge and download button. It only becomes active once at least two files are selected.
- Your browser downloads the resulting
sloucene.pdffile with all pages joined together.
| Input | Output |
|---|---|
| contract.pdf (3 pages) + attachment.pdf (2 pages) | merged PDF (5 pages: 1–3 from the contract, 4–5 from the attachment) |
What Merge PDF is good for
Merging PDFs is useful whenever you need one complete file out of several partial documents. Typical scenarios:
- Scanned documents — a scanner often saves each page as a separate PDF; join them into a single document for archiving or sending.
- Invoices and receipts — combine a month of accounting documents into one email attachment.
- Contracts with attachments — merge the main document and its appendices into a single file for signing.
- Study materials — assemble individual chapters or lectures into one set of notes.
Because the tool works entirely in your browser, your files stay private — sensitive contracts, invoices, or personal documents are not uploaded to any server and no one else can access them. Tip: if you want a different order, select the files in the desired sequence, or rename and sort them beforehand.
FAQ
How many PDFs can I merge at once?
There is no fixed limit on the number of files — you can merge two or many documents. The practical limit is your device's memory, since all files are processed in the browser; with very many or very large PDFs the operation may take a moment.
In what order are the pages joined?
Files are merged in the order your browser selects them, and you can see that order in the list below the file picker. If you need a specific sequence, select the files in the desired order or rename them beforehand so they sort alphabetically.
Are my files uploaded to the internet?
No. The entire merge happens locally in your browser using JavaScript. Your PDFs are not loaded to any server, so even sensitive contracts or invoices stay only on your device.
Does merging reduce the document's quality?
No. The tool copies the original pages — including text, images, and vector graphics — without change. There is no conversion to an image and no recompression, so the result is visually and data-wise identical to the inputs.
Can I select only certain pages from each PDF?
No, this tool always joins every page of each selected file. If you need only part of a document, first extract the pages with the Split PDF tool and then merge the result.
Why is the Merge button inactive?
Merging only makes sense with two or more files, so the button activates only after at least two PDFs are selected. If you have only one file selected, add another.
Are links, bookmarks, and form fields preserved?
Complete pages are copied with their content and appearance. Document-wide interactive elements, such as the bookmark tree or some form fields, may not carry over during a simple page merge; the visual page content is always preserved.
Does the tool work on mobile and without installation?
Yes. It runs in an ordinary browser on both computer and phone, requiring no installation or registration. On mobile you pick files through the system document picker.
Sources & standards
📅 Last updated: 11 July 2026