Merge PDF
Combine PDFs in any order, with optional page-size standardization — nothing leaves your browser.
Assembling a document from multiple PDFs usually means uploading your files to a cloud service, waiting, and hoping nothing sensitive leaks. This tool takes a different approach: your PDFs are read directly in the browser using pdf-lib, merged in the order you choose, and handed back to you as a download — the server is never involved. Drag the grip handle on any row to reorder files, and use the Page size option to normalize a mix of A4, Letter, landscape slides, and portrait pages into one uniform format before merging.
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How to Use
- 1
Drop two or more PDF files onto the upload area, or click to browse. Files from different sources — different page sizes, orientations, or applications — all work.
- 2
Drag the grip handle (⠿) on any row to reorder the files. Drag-and-drop works with a mouse and with touch on mobile.
- 3
Choose a page size option. "Keep original sizes" merges pages as-is. "Standardize" lets you pick A4 or Letter and an orientation — each source page is scaled to fit the target size, centered, with text still sharp.
- 4
Click "Merge PDFs". The tool combines all pages in the chosen order and generates the output in your browser.
- 5
Download the merged PDF. Use the Edit PDF or Split PDF shortcut to continue working on it.
Frequently Asked Questions
How many PDFs can I merge at once?
There's no hard limit. You can merge as many files as your browser's memory comfortably handles — typically dozens of PDFs or hundreds of pages with no issues.
Will merging affect my PDF quality?
No. In Keep original sizes mode the tool copies each page byte-for-byte. In Standardize mode, pages are embedded as vector form objects on the target page, so text, fonts, and vector graphics remain fully sharp and selectable at any zoom level.
What does "Standardize" do exactly?
It creates a new blank page of the target size (A4 or Letter), then draws each source page onto it at the largest scale that fits while keeping the original aspect ratio, centering the content. The orientation setting controls whether the target page is portrait or landscape — Auto picks per-page based on each source page's own proportions.
Can I merge password-protected PDFs?
Not currently. Remove the password protection in your PDF viewer first (e.g. File → Print → Save as PDF in Chrome, or use Preview on Mac), then use this tool.
Are my PDFs uploaded anywhere?
No. Everything runs entirely in your browser using pdf-lib (MIT license). Your files are never sent over the network.