PDF Merge

How merging works. Each PDF is opened in your browser with the pdf-lib library, the chosen pages are copied into a new document, and the new PDF is saved for download. Page content is copied as-is, so text stays selectable and searchable, images keep their resolution and nothing is re-rendered or compressed. Pages of different sizes, such as A4 and US Letter, keep their own sizes in the merged file.

Order. "As selected" uses the order the files arrive from your file picker, which on most systems follows the order you clicked or the sort order of the folder view. "By file name" sorts naturally, so 2-cover.pdf comes before 10-appendix.pdf, where plain alphabetical sorting would put 10 first. Numbering files 01, 02, 03 makes either order predictable.

Choosing pages. Leave the page box empty to include every page. To pick pages, enter one line per file, in the same order as the files:

• 1-3 keeps pages 1 to 3;
• 1, 3, 7 keeps those pages;
• 5-end keeps page 5 to the last page;
• a blank line or "all" keeps the whole file.

Pages keep the order you write, and a range outside the file's length is reported as an error with the file's real page count rather than silently skipped.

What is not kept. Merging copies pages, not the whole document structure:

• Bookmarks (the outline panel) and links that jump between files are dropped.
• Fillable form fields may stop working or lose their values, so fill and flatten forms before merging.
• Digital signatures become invalid, because the document has changed; signed contracts should be merged before signing, or kept as separate files.
• Document properties such as the title come from none of the originals.

Password-protected files. PDFs with an open password, or with encryption that restricts editing, cannot be read for merging. The tool reports which file is protected; open it with the password and save an unprotected copy first, if you are entitled to.

File size. The merged file is roughly the sum of the pages you kept. Fonts and images shared between files are not de-duplicated, so merging many files that embed the same font can be a little larger than expected. Scanned documents are mostly images, and their size depends on the scan resolution.

Privacy and limits. Files are read into your browser's memory and never uploaded, which makes it suitable for invoices, contracts and medical letters. The practical limit is your device's memory: hundreds of pages are fine on a laptop, while very large scanned files can be slow on phones.

Checking the result. Open the merged PDF and check the page count and order before sending it. The result line lists each file and how many of its pages were included, which makes a missing page range easy to spot.

A report and an invoice

Inputs: PDF files: report-a4-3pages.pdf, invoice-letter-2pages.pdf; Order: As selected

Choose report-a4-3pages.pdf and invoice-letter-2pages.pdf, keep the order as selected and leave the page box empty. All 5 pages are included; the merged file was checked: three A4 pages followed by two Letter pages.

Result: Merged 2 files → 5 pages, 1.7 KB 1. report-a4-3pages.pdf: 3 of 3 pages 2. invoice-letter-2pages.pdf: 2 of 2 pages Bookmarks, form fields and links between files are not kept. Files never leave your browser.

Keeping selected pages

Inputs: PDF files: report-a4-3pages.pdf, invoice-letter-2pages.pdf; Order: As selected; Pages to keep, one line per file in order: "1, 3 ⏎ 2"

Choose the same two files, order pick, and enter "1, 3" on the first line and "2" on the second. Pages 1 and 3 of the report and page 2 of the invoice give a 3-page PDF.

Result: Merged 2 files → 3 pages, 1.3 KB 1. report-a4-3pages.pdf: 2 of 3 pages 2. invoice-letter-2pages.pdf: 1 of 2 pages Bookmarks, form fields and links between files are not kept. Files never leave your browser.

Sorting by file name

Inputs: PDF files: 10-appendix.pdf, 2-cover.pdf; Order: By file name (A–Z, natural)

Choose 10-appendix.pdf and 2-cover.pdf and set the order to name. Natural sorting puts 2-cover first, as a person would expect, although plain alphabetical order would put 10 first.

Result: Merged 2 files → 2 pages, 1.1 KB 1. 2-cover.pdf: 1 of 1 page 2. 10-appendix.pdf: 1 of 1 page Bookmarks, form fields and links between files are not kept. Files never leave your browser.

Are my PDFs uploaded?

No. They are merged in your browser.

Can I choose which pages to include?

Yes, with ranges like 1-3, 5 or 5-end, one line per file.

Does merging reduce quality?

No. Pages are copied without re-rendering.

Can it merge password-protected PDFs?

No. Save an unprotected copy first.

Are bookmarks kept?

No. Bookmarks and cross-file links are dropped.

Is there a file limit?

Only your device memory.