Merge PDF

Combine multiple PDF files into a single document, in any order you choose. Everything runs in your browser — nothing is uploaded.

Combine your PDFs

Add two or more PDF files, arrange them in the order you want, then merge.

Drag & drop PDF files here, or click to browse
You can add PDFs one at a time or select several at once.

    Merged file ready

    Combined PDF
    0 pages
    Your files are processed locally in this browser tab using JavaScript. They are never uploaded to Calcooo or any server.

    How to use this tool

    1. Drag and drop your PDF files into the box above, or click to browse and select them.
    2. Use the up/down arrows on each file to set the order you want in the final PDF.
    3. Press Merge PDFs to combine them into a single file.
    4. Click Download merged.pdf to save the result to your device.

    FAQ

    Frequently asked questions

    Is my PDF uploaded to a server when I merge it?

    No. Merging happens entirely inside your browser using JavaScript. Your files never leave your device.

    Can I change the order of the PDFs before merging?

    Yes. Use the up and down arrows next to each file in the list to reorder them before merging.

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

    There's no fixed limit, but very large files depend on your device's available memory since everything is processed locally.

    Will merging affect the quality of my PDFs?

    No. Pages are copied as-is, so text, images and formatting stay exactly as they were in the original files.