Merge PDF files into one document
Combine two, ten or a hundred PDFs into a single file. Files are joined in the order shown; remove any you do not want. The merge runs on your device using pdf-lib, so even large scans finish in seconds and nothing is uploaded.
How to use the Merge PDF
- Drop all the PDFs you want to combine (you can add more in several goes).
- Check the order in the list; remove any file with ×.
- Click Merge PDFs.
- Download merged.pdf.
How merging works
A PDF is a container of pages plus shared resources (fonts, images). Merging copies every page from each source document into a new document, carrying the resources each page needs. This tool uses pdf-lib, an open-source PDF library, compiled to run in your browser. Because pages are copied rather than re-rendered, text stays selectable, links keep working and quality is unchanged.
Order and structure
Files are merged in the order listed. Add them in the order you want, or remove and re-add to fix the sequence. Bookmarks (outlines) from the source files are not carried into the merged file; form fields are copied as static appearance.
Password-protected PDFs
Files protected against opening cannot be merged until unlocked with their password. Files that only restrict printing or copying are merged normally.
Size and speed
Because there is no upload, a 200 MB scanned book merges as fast as your computer can read it, usually a few seconds. The output is not recompressed, so its size is roughly the sum of the inputs. Use the compress tool afterwards if you need a smaller file.
Common uses
- Joining a signed cover letter to a CV before applying.
- Combining scanned receipts into one expense report.
- Assembling chapters exported separately from a word processor.
- Stitching together forms for a visa or mortgage application.
Frequently asked questions
Is there a limit on the number of PDFs?
No practical limit. Up to 500 files can be selected at once and you can add more before merging.
Does merging reduce quality?
No. Pages are copied as-is; images and text are not re-encoded.
Are my PDFs uploaded?
No. The merge happens in your browser. The page keeps working with the internet disconnected.
Can I merge PDFs with different page sizes?
Yes. Each page keeps its original size and orientation.
Privacy
This tool runs entirely inside your browser using WebAssembly and the Canvas/File APIs. Your files are never uploaded to ToolFlint or any third party; you can verify this in your browser's network tab or by switching to airplane mode after the page loads. Read how we process files.
Last updated 2026-09-23.