Combine PDF

How to use Combine PDF

Key features of Combine PDF

About Combine PDF

Combine PDF builds one document from pages you pick out of two or more PDFs. When you add a file it is opened once with pdf-lib to count its pages, so the Pages box can check your selection against the real page count. On Combine Pages the selected pages are copied, file by file in list order, into a new document saved as combined_pages.pdf. Nothing is re-rendered or compressed, and bookmarks are not carried over.

Use it to put the first two pages of one report in front of the appendix of another, pull one exhibit each out of several scanned contracts, or place a cover page from a template ahead of an existing file. If you want every page of every file, Merge PDF does that with a simpler list; Combine PDF is for when only some pages should make it into the result. A page number outside a file's range is flagged next to that file and keeps Combine Pages greyed out, instead of producing a wrong file.

When to use Combine PDF

A grant application asks for the budget pages of last year's report and the cover page of this year's. Add both reports, type 14-16 in the Pages box of the old one and 1 in the box of the new one, and Combine Pages produces a four-page file in that order.

You need pages 5 to 9 of one long manual as a document of their own. Add just that file, type 5-9, and combine. The tool works with a single file as well as several, and it understands ranges, which Extract PDF Pages does not.

A signature page has to follow each of two agreements bundled in one PDF: the first agreement is pages 1 to 4, the second 5 to 8, and the signature page is 9. Type 1-4, 9, 5-8, 9 and page 9 is copied twice, once after each agreement.

When every page of every file belongs in the result, Merge PDF is quicker: no Pages boxes to fill in, and up and down arrows to reorder the files. Combine PDF has no arrows. Files are joined in the order they were added, so add them in the order you want, or remove one and add it again to move it to the end.

Tips and troubleshooting

• Each file is opened once when it is added, to count its pages. A file that cannot be opened (damaged, or not a PDF) shows could not read this file, its Pages box is disabled, and Combine Pages stays greyed out until you remove that file.
• A password-protected file, or one that opens without a password but restricts changes, is encrypted, and pdf-lib cannot decrypt it, so its pages would come out blank. The list marks it encrypted in red, its Pages box is disabled, and Combine Pages stays greyed out until you remove it. Remove the protection with Unlock PDF, then add the unlocked copy.
• The count next to each file updates as you type. An entry that is not a number or a range, such as p5, replaces the count with a red note, and Combine Pages stays greyed out until the box is corrected.
• Accepted entries are a single number (5), a range (2-6), an open range to the end (8-) or from the start (-3), and the word all in any case. Spaces are ignored. A backwards range such as 6-2 is refused.
• A selection that does not fit the file, such as page 12 in a 10-page file or the backwards range 9-4, is caught the same way: the note reads Page 12 is outside 1-10, and no file is written until the box is fixed.
• The output is named combined_pages.pdf and the result message states how many pages came from how many files. Process Another File clears the list and shows the upload zone again without reloading the page.
• The guide how to merge PDF files without uploading them covers files that will not open, what is kept and lost when pages are copied, and what to do when the result is too large.

How Combine PDF works in your browser

Adding a file triggers one read: its bytes are loaded into pdf-lib with the encryption check switched off, only to ask whether the file is encrypted and how many pages it has. The page count is stored next to the file name so the Pages box can be checked against it. On every keystroke in a Pages box, the text is parsed into a list of zero-based page indices, and the number you see beside the file is the length of that list, or the parser's message when an entry does not fit.

On Combine Pages, all the selections are parsed again first, so a bad entry stops the job before any output exists. A new pdf-lib document is then created and, file by file in list order, each source is loaded from memory again and the chosen pages are copied in, with their fonts and images. The document is saved to bytes, wrapped in a Blob, and offered as combined_pages.pdf; Preview Document shows that Blob in your browser's own PDF viewer. Both reads happen inside the tab, and no bytes are sent anywhere.

Frequently asked questions