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PDFNova

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Merge PDF files

Put several PDFs together into a single document — lecture handouts into one study pack, a cover letter in front of a CV, or monthly statements into a yearly file. Set the order first, then merge.

Your files never leave this device.

Everything runs in this browser tab — there is no upload step and no server that could receive your document. To check: once this page has loaded, turn off Wi-Fi or switch your browser to offline mode, then use the tool. It still works. More ways to verify

or drop them here — add two or more, in any order

How to use

  1. Choose two or more PDF files, or drop them onto the box. You can add more at any time.
  2. Set the order: drag a file by its handle, or use the up and down arrows (these also work from the keyboard).
  3. Remove anything you added by mistake with the bin icon.
  4. Select Merge, then Download. The file is saved as merged.pdf; rename it as you like.

How it works

Each file is read into memory and parsed with pdf-lib, an open-source PDF library that runs in JavaScript. A new, empty document is created, and the pages of every source file are copied into it in your chosen order. Copying a page brings along everything that page needs to display — its content stream, fonts, images and other resources — so pages look the same as they did in the original.

The new document is then written out with compressed object streams and handed to your browser as a download. At no point is a file sent anywhere: the work is done by code running in this tab.

Worked example

Suppose you have intro.pdf (2 pages), chapter.pdf (14 pages) and appendix.pdf (3 pages) and you add them in the wrong order: appendix, intro, chapter. Moving intro to position 1 and appendix to position 3 gives a 19-page file where pages 1–2 are the introduction, 3–16 the chapter and 17–19 the appendix.

Limitations

  • Bookmarks (outlines) and the document-level table of contents from the source files are not carried over; page content is.
  • Interactive form fields may stop working or lose their values after merging, because forms are defined for the whole document rather than per page.
  • Encrypted or password-protected PDFs cannot be merged until the protection is removed.
  • Everything happens in memory. Very large combined sizes (hundreds of megabytes) can exhaust memory on phones.

Questions

Is there a limit on how many files I can merge?

There is no fixed limit. The practical limit is your device's memory, because all files are held in memory while merging. A few hundred megabytes in total is usually fine on a laptop.

Will merging reduce the quality of my pages?

No. Pages are copied as they are, including their fonts and images. Nothing is re-rendered or re-compressed.

Can I merge only some pages of a file?

Not directly in this tool. Use Extract pages first to make a PDF of just the pages you want, then merge that file.

Why did my merged file lose its bookmarks?

Bookmarks belong to the whole document rather than to individual pages, and this tool only copies pages. The visible content is unchanged.

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