Merging is the PDF task people do most often, and it usually goes right. When it goes wrong, the cause is nearly always one of three things: files in the wrong order, a navigation structure that disappeared, or a photo that ended up as a postage stamp in the middle of a page.
This guide walks through Merge PDF in TokPDF, explains exactly what happens to bookmarks and images, and covers two special cases: interleaving double-sided scans and reordering individual pages. Everything runs in your browser, so the files are not uploaded.
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Merge files in five steps
Open Merge PDF and add at least two files. You can add up to 100 at a time, and you can keep adding more before you merge.
Put the files in order. Drag a row to move it (with a mouse you can grab anywhere on the row; on a touch screen use the grip handle), or use the up and down arrows on larger screens.
Leave Preserve bookmarks switched on if you want one bookmark per file in the result. The next section explains what this does and does not do.
Click merge. Office documents are converted first, so a merge with Word or Excel files takes longer than one with PDFs only.
Download the result, called merged.pdf, and rename it to something meaningful before you share it.
Getting the order right
Files appear in the list in the order you selected them. Most file pickers add files in the order they are shown, which is often alphabetical, but that is not guaranteed across operating systems. TokPDF has no sort-by-name button, so check the list before merging.
If you merge the same kind of bundle regularly, such as invoices for an expense claim, prefix the file names with numbers: 01-cover.pdf, 02-invoice-march.pdf and so on. They then sort predictably everywhere, and the names double as clean bookmark titles.
The list orders whole files. To move individual pages, merge first and then open the result in Organize PDF, where you can drag page thumbnails, duplicate pages and delete the ones you do not need.
What happens to bookmarks
With Preserve bookmarks (create bookmark for each file) on, which is the default, TokPDF adds one bookmark per input file. Each bookmark is titled with the file name and jumps to that file’s first page. For a bundle of separate documents this is exactly what readers need: a sidebar list they can click through.
What it does not do is copy the bookmarks that already exist inside your source PDFs. If you merge three reports that each have a detailed chapter outline, the result has three top-level bookmarks, not the chapters. That is a limitation worth knowing before you merge long structured documents.
If you need a deeper outline, add or edit bookmarks afterwards with the Bookmark tool, or generate them from the document’s headings with Auto Generate Bookmarks.
Mixing images, text and Office files
Merge PDF accepts more than PDFs: JPG, PNG, WebP, BMP and SVG images; TXT and Markdown text; Word, Excel and PowerPoint files, including the OpenDocument formats, RTF and CSV. Non-PDF files are converted on your device, and the result is merged in the order you set.
Images are placed on an A4 page with a half-inch margin. The page is turned to landscape for wide images, and each image is centred and scaled down to fit, but never enlarged. A 600-pixel-wide screenshot therefore sits small in the middle of the page. JPG and PNG images are embedded without re-compression, so their quality is unchanged.
If you need a different layout, such as Letter-size pages, no margins, or pages that match the photo size exactly, convert the images first with Image to PDF, which has page size, orientation and margin settings, then merge the resulting PDF.
- Text files are set in 11-point type on A4 pages. Fine for logs and notes, not for anything that needs styling.
- Office documents are converted with LibreOffice running in your browser. The first conversion downloads the engine, which is large, so expect a wait on slow connections. Each Office file can be up to 50 MB.
- Fonts that are not available to the converter are substituted, so Word files with unusual fonts may reflow. When the layout matters, export to PDF from Word itself and merge that PDF.
Double-sided scans: interleave instead of merge
A scanner without duplex support gives you two files: all the front sides, then all the back sides, usually in reverse order because you flipped the stack. A normal merge puts them one after another, which is wrong.
Alternate & Mix PDF takes page 1 of the first file, then page 1 of the second, then page 2 of each, and so on. Tick Reverse second document when the back sides were scanned last page first. The option reverses the second file only, so add the fronts first.
Things to check before you send a merged file
- Forms. Fillable fields from different source files may not work reliably after merging. Fill the forms first, then use Flatten PDF to lock the answers in before merging.
- Internal links. A clickable table of contents inside one of the source files can stop pointing at the right page. External web links are not affected.
- Mixed page sizes. A4 and US Letter pages, or landscape slides next to portrait reports, merge fine but print inconsistently. Fix Page Size can make them uniform.
- Password-protected inputs. TokPDF asks for each password when you add the file. The merged result has no password; add one with Protect PDF if needed.
- File size. Merging adds sizes together. If the result is too big to email, see how to compress a PDF.
Frequently asked questions
How many files can I merge at once?
Are my original bookmarks kept?
Can I merge only certain pages of a file?
Does merging reduce image quality?
Are my files uploaded to a server?
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Opens the tool in your browser. No sign-up needed.