Merge PDF Files
Combine two or more PDFs into a single document in seconds. Everything happens in your browser — your files are never uploaded anywhere.
When do you need to merge PDFs?
Combining PDFs comes up constantly: joining a cover letter and résumé into one application file, stitching scanned pages back into a single document, assembling invoices or receipts for an expense report, or bundling several signed forms into one attachment because a portal only accepts a single upload. Instead of installing desktop software or trusting a random upload site with private paperwork, this tool joins the files locally on your own device.
| Scenario | Typical order |
|---|---|
| Job application | Cover letter → résumé → certificates |
| Expense report | Summary sheet → receipts in date order |
| Scanned document | Pages in reading order (check for upside-down scans first) |
| Contract package | Main contract → appendices → signature pages |
Why the order matters
The merged PDF simply places every page of the first file, then every page of the second, and so on. There is no way to reorder pages after merging without splitting the file again — so it's worth a few seconds to arrange the list before you click merge. Use the ↑ and ↓ buttons next to each file to move it, and ✕ to remove one you added by mistake. The page count shown next to each file helps you confirm you picked the right version.
Mixed page sizes are the mistake nobody sees until it prints
A PDF does not have "a" page size — every page carries its own. Merge an A4 report with a Letter-size invoice and a landscape scan, and the result is a single valid document whose pages are three different shapes. On screen it looks fine, because the viewer scales each page to the window. It goes wrong at the printer, where the mismatch becomes shrunken pages, unexpected margins, or a "scale to fit" dialogue that quietly reduces everything.
A4 and US Letter differ by about 6 mm in width and 18 mm in height — close enough to look identical on screen and far enough apart to be obvious on paper. If the merged file is destined for print, check that everything going in shares a page size, or standardise it before merging rather than after.
What merging keeps, and what it quietly leaves behind
Pages are copied whole, so nothing is re-compressed: text stays selectable and images keep their original quality. The document-level furniture is what does not come along.
- Bookmarks and outlines belong to each source document and do not carry over into the merged one.
- Form fields may lose their values, and two forms with identically named fields can collide.
- Internal links pointing at pages that ended up in a different position will not follow them.
- Digital signatures are invalidated. A signed document is signed as a whole file; merging creates a new one, so the signature no longer covers it. That is by design.
And the merged file is usually a little larger than the sum of its parts, not smaller: each source brings its own embedded fonts, and identical fonts from different documents are not automatically merged into one.
Frequently asked questions
Are my PDFs uploaded to your server?
No. The files are read and combined entirely inside your browser using JavaScript — they never leave your device. Nothing is stored, logged, or transmitted.
Is there a limit on file size or number of pages?
There's no artificial limit, but the work happens in your browser's memory, so very large jobs (hundreds of megabytes or thousands of pages) can be slow or fail on low-memory devices. Everyday documents — even a few hundred pages — merge in a second or two.
Does merging re-compress or reduce quality?
No. Pages are copied into the new file exactly as they are — text stays sharp and searchable, and images keep their original quality. The merged file is roughly the sum of the originals' sizes.
Can I merge password-protected PDFs?
Not directly. Encrypted PDFs can't be read without the password, so you'll see a friendly error. Remove the password first (for example, by re-saving the file from a PDF viewer after unlocking it), then merge.
Can I change the page order inside a single file?
This tool orders whole files, not individual pages. To rearrange pages within one PDF, use our Split PDF tool to extract ranges, then merge them back in the order you want.