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

No hard limit. The practical limit is your device’s memory. Hundreds of normal documents are fine.

Are my files uploaded?

No. This tool runs entirely in your browser tab. Files are read from your disk into memory and the result is generated locally.

Is it free? Are there limits or watermarks?

Free and open source (MIT). There are no file-size caps, daily quotas, accounts or watermarks.

Does it work offline?

Yes, once the page (and any engine it needs) has loaded, it keeps working without a connection thanks to the service worker cache.

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Merge PDF

Combine multiple PDFs into one ordered document with drag-and-drop sorting.

Free, no uploads, no sign-up. Runs 100% in your browser.

How Merge PDF works

Merge PDF runs entirely in your browser. Combine multiple PDFs into one ordered document with drag-and-drop sorting. Under the hood it uses pdf-lib (a pure-JavaScript library that creates and edits PDF structure (pages, text, images, forms)) and PDF.js (Mozilla’s PDF renderer, used for thumbnails, previews and text extraction (runs in a Web Worker)). Your files are read into this tab’s memory, processed on your own CPU, and handed back to you as a download. Nothing is sent to a server.

Input: PDF. Output: PDF.

How to use Merge PDF

Drop two or more PDFs (add more at any time with “Add files”).
Drag the cards to set the order, or sort by name.
Optionally rotate a file or limit it to a page range.
Press Merge and download the combined PDF.

Tips

Use page ranges like “1-3, 7” to take only the pages you need from each file.
Bookmarks are not carried over; add page numbers afterwards if you need references.

Merge PDF FAQ

Is there a limit on how many PDFs I can merge?: No hard limit. The practical limit is your device’s memory. Hundreds of normal documents are fine.
Are my files uploaded?: No. This tool runs entirely in your browser tab. Files are read from your disk into memory and the result is generated locally.
Is it free? Are there limits or watermarks?: Free and open source (MIT). There are no file-size caps, daily quotas, accounts or watermarks.
Does it work offline?: Yes, once the page (and any engine it needs) has loaded, it keeps working without a connection thanks to the service worker cache.

Related tools

Organize PDF: Visually reorder, rotate, duplicate and delete pages with thumbnails.
Compress PDF: Shrink PDF size with smart image downsampling and stream compression.
Add Page Numbers: Stamp page numbers with position, format and font controls.
Split PDF: Split by ranges, every N pages, or extract each page into a ZIP.