Merge PDF
Combine multiple PDFs into one file, in the order you choose. Files are processed in your browser.
Drop PDF files here, or click to choose.
Add two or more PDFs · nothing is uploaded
How to merge PDF files
- Add your files. Choose two or more PDFs using the area above. You can add another file before you merge.
- Set the order. Use the arrow buttons beside each file. The first file in the list supplies the first pages in the result.
- Merge and download. Select "Merge & download." Your browser assembles the new PDF and saves it as
merged.pdf.
What happens to your files
This PDF merger runs locally in the browser. Selecting a document reads it into your device's memory; JavaScript in the current tab copies its pages into a new PDF and sends that result to your downloads. The document content is not uploaded to OpenToolkit for processing or stored on an OpenToolkit server.
This local approach avoids an upload queue and a server-side file-size rule. Your practical limit depends on the memory available to the browser, so a very large document or a phone with limited memory may still run out of resources. Refreshing or closing the page clears the files held by the tool.
What this PDF merger supports
Common reasons to combine PDFs
- Put an application, identification and supporting documents into one upload.
- Collect monthly receipts or invoices into a single accounting file.
- Join chapters or sections exported separately from another application.
- Reassemble documents after using the Split PDF tool.
Frequently asked questions
Are my PDFs uploaded anywhere?
No. The merge is performed in the current browser tab using your device's processor and memory. The selected document content is not sent to OpenToolkit for processing.
Is there a file-size or page limit?
OpenToolkit does not set an upload limit because there is no file upload. Available browser memory is the practical limit. If a large merge fails, close other tabs or combine smaller groups first.
Can I merge a password-protected PDF?
Not directly. Unlock the document in a PDF application, save an unprotected copy, and then add that copy to the merger.
Will merging reduce the page quality?
The merger copies PDF pages into a new document instead of converting them to screenshots. It does not intentionally downsample images. If the result needs to be smaller, use Compress PDF afterward.
What happens to bookmarks and digital signatures?
Document-level features such as outline bookmarks are not preserved reliably when pages are copied. A cryptographic signature applies to the exact original file and cannot remain valid after that file is changed. Merge first, then sign the finished PDF.
Can I reorder individual pages?
This tool arranges whole files. Use PDF Organizer to rotate, remove, duplicate or reorder individual pages.
Related guides
Last reviewed: August 2026