How Merge PDF works
Merging copies every page of each PDF, in the order you added the files, into a single new document. Nothing on the pages is re-rendered: text stays selectable, vector drawings stay sharp and images keep their original quality, because the page contents are copied rather than redrawn.
The work is done by pdf-lib, an open-source PDF library, running inside this tab. The files are read from your device into memory and the merged PDF is built there, so confidential contracts, statements and scans never pass through a server.
What a merge does not keep is the document-level extras of the individual files: bookmarks and outlines, and form fields that belong to a particular file, are not carried into the merged document. The pages themselves are complete.
Because merging runs on your own device, it also works for files you would rather not upload anywhere: medical records, tax returns, signed contracts and identity documents. The merged file is saved as a standard PDF that opens in Adobe Acrobat, Preview on a Mac, Microsoft Edge, Chrome and every phone. Page sizes are kept as they were, so an A4 letter and a US Letter form in the same merge each keep their own size, and landscape pages stay landscape. There is no watermark, no cover page and nothing added to the document.
Merge PDF options explained
| Order | Files are merged in the order they appear in the list. Add them in the order you want. |
|---|---|
| Page content | Copied exactly: text, images, vector graphics and annotations on the page. |
| Bookmarks | Not carried over from the original files. |
| Password-protected PDFs | Cannot be merged; remove the password first. |
| Limit | The memory your browser allows one tab, usually a few hundred megabytes of PDFs. |
When to use it
People merge PDFs to send one attachment instead of several, to combine scanned pages that came out as separate files, to assemble an application pack from a form, an ID copy and a letter, or to put monthly statements into a single yearly file.
Add the files in the order you want them, because that order is kept. If a scanner produced one file per page, name the files with numbers first (01, 02...) so they sort correctly when you select them all at once.
About these PDF tools
The page tools, from merge and split to crop, resize, watermark and page numbers, use pdf-lib, an open-source JavaScript library that reads the structure of a PDF and writes a new one. Because it works on the page objects themselves rather than on pictures of them, text stays text, fonts stay embedded and vector drawings stay sharp, and nothing is added to your pages that you did not ask for. None of these tools edit what is already printed on a page: to change wording or fill a form, use a PDF editor. Password-protected PDFs must be unlocked first, since the pages cannot be read without the password. Every tool works on a copy, so the file on your device is never changed.
Merge PDF troubleshooting
One file will not add
It is probably password protected or damaged. Open it in your PDF reader; if it asks for a password, remove it there and save a new copy, then add that copy.
The merged file is very large
Merging adds the sizes together, and scanned pages are big. Merge first, then shrink scans by converting pages to JPG and back to PDF at a lower resolution.
Pages are in the wrong order
The list order is the page order. Clear the list and add the files again in the order you want, or number the file names so they sort correctly.
How to use Merge PDF, step by step
- Press "Choose PDF files" or drag PDFs onto the box.
- Set the options if you need to; the defaults suit most uses.
- Press "Merge PDFs". The work happens on your device.
- Save the result with its download button.
Is it safe to do this online?
With most online tools, "online" means your file is uploaded to a company's server, processed there and kept for a while before it is deleted. Here it is not. The page downloads the tool's code to your browser, and your file is read and processed inside the tab on your own device. It is never sent to TapToConvert or anyone else.
You can check this yourself: once the page and its engine have loaded, turn off Wi-Fi and the tool still works. That also means there is no queue, no daily limit and no file size cap set by a server; the only limit is the memory your browser gives a single tab.
Merge PDF FAQ
Is there a limit on how many PDFs I can merge?
No fixed limit. The practical limit is the memory your browser gives one tab, which comfortably handles dozens of normal PDFs.
Will the merged PDF lose quality?
No. Pages are copied, not re-rendered, so text, images and drawings are exactly as they were.
Can I change the order after adding files?
Remove files and add them again in the order you want; the list order is the page order.
Can I merge password-protected PDFs?
No. Encrypted PDFs cannot be opened without the password; remove it in your PDF reader first.
Is it free?
Yes. No sign-up, no watermark and no limit on use. TapToConvert is supported by advertising.
Are my files uploaded?
No. Everything happens inside your browser tab, on your own device.