Merge PDF

How do you combine several PDF files into one document?

Choose two or more PDFs, arrange the file list, and run the merge to download one document. Each source contributes its selected pages in sequence: the tool does not interleave pages between files. Leave Pages (optional) blank for complete documents, or select only the pages needed for the final packet. This is useful when a report needs a cover, selected report pages, and supporting material in a specific order.

For example, put Cover.pdf first, Report.pdf second, and Appendix.pdf third. Suppose they contain one, seven, and five pages respectively. Use the selections below to produce an eight-page document. The list header shows the selected page total, so check that total before running the merge.

Example packet assembled in file-list order

Source	Pages (optional)	Pages included	Position in result
Cover.pdf	Blank	1	1
Report.pdf	1-3,7	4	2–5
Appendix.pdf	3-	3	6–8

With bookmarks enabled, the new outline contains Cover, Report, and Appendix. Their destinations are result pages one, two, and six. The Appendix bookmark points to its first included page, even though that page was originally page three of the source. Changing the file order changes both the output sequence and these destinations.

How do page ranges and file ordering work?

Page numbers start at one. Separate selections with commas and use a dash for an inclusive span. An open end selects through the last page; an omitted start selects from the first page. The parser preserves the order in which you write entries, rather than sorting them automatically. A repeated page is kept once within that file's selection, so overlapping ranges do not duplicate it.

A reversed span, an out-of-range page, or an empty entry between commas produces a message beneath the field. Correct the input before merging: the merge button is disabled while any selection is invalid. Selecting a subset changes the number of pages contributed, but it does not remove the source file from the list.

For document order, Sort alternates between ascending and descending file-name order. Reverse flips the current list. Drag rows with a fine pointer, use the visible arrow buttons on touch devices, or focus the row itself and press Alt+ArrowUp or Alt+ArrowDown. These controls move whole files; use the range field when changing the sequence of pages within a source.

How does PDF merging preserve pages and create bookmarks?

The engine uses pdf-lib to create a new PDF, load each source, copy the chosen pages, and append them to the output. It copies PDF pages rather than rendering screenshots of them. There is no page-resizing or image-compression step in this merge path; pages retain their source dimensions and orientation. Combining portrait and landscape pages therefore does not normalize them to one paper size.

Source bookmark trees are not imported. Instead, Add a bookmark for each file builds a fresh outline with one entry per source and uses its file name without the .pdf extension. The option starts checked. Turn it off when the result should contain no generated outline. Do not treat merging as a complete migration of document-level features: inspect important navigation in the downloaded document before distributing it.

How do you unlock encrypted PDFs before merging?

An encrypted source stays in the list with Password required instead of a page-range field. Enter the password and choose Unlock, or submit with Enter. The field clears as the attempt begins. After a successful local decryption, the row shows Unlocked, its page count, and the range input. A failed attempt reports an incorrect password or unsupported encryption.

All locked files must be unlocked or removed before merging. The resulting PDF is a newly created document saved without password protection; unlocking a source does not add encryption to the output. Keep that difference in mind when assembling material that previously required a password to open.

When is merging useful, and how should you handle large sets?

Combine a cover and appendices with a business report, assemble exhibits after a contract, place a bibliography after a paper, or collect invoices into one archive. Choose the intended reading order first, then select pages that belong in the packet. Merging organizes existing pages; it does not write a cover, summarize documents, or add page numbers.

Documents are read into browser memory, and the engine processes sources sequentially before saving the result. There is no explicit file-count or byte-size ceiling in this path, but available memory still constrains a batch. Avoid assuming a particular number of files will finish within a fixed time. If a large set fails, try smaller groups and inspect each intermediate result before combining them.

What happens after the merged PDF is ready?

The completion screen shows the result's page count and file size. Edit the output file name if needed and choose Download. Share appears only where the browser supports sharing files of this type. Choose Merge another set of PDFs to start a new batch. The tool releases the stored source byte arrays after a successful merge while retaining the result for download.

File reading, unlocking, and merging run locally without uploading documents for processing. Content Security Policy permits connections only to this site. For further work, use Split PDF to extract pages or Rotate PDF to change page orientation. The PDF Tools category lists the other document operations separately.