Merge PDF

Combine multiple PDFs into a single file. Drag to reorder before merging.

ToolLast updated ·Reviewed by the OnlineFileConverter team

Add PDF files to merge

About this tool

Merging PDFs is one of the most common document tasks — combining a cover letter with a resume, joining scanned invoices into a single file for an expense report, or stitching together chapters of a manuscript. Our PDF Merger does it entirely in your browser using the open-source pdf-lib library, which means your documents never leave your device.

Unlike server-based mergers, there's no upload step, no daily limit, and no file-size ceiling beyond your device's available memory. You can reorder pages with simple up/down controls before merging, and the output preserves the original page sizes, embedded fonts, hyperlinks, and form fields of each source PDF.

Because the entire process runs locally, this tool is safe for sensitive documents — contracts, financial statements, medical records, or anything else you wouldn't want sitting on a third-party server.

Why use it

  • 100% private — PDFs never leave your browser.
  • Drag-to-reorder before merging.
  • Preserves fonts, hyperlinks, and form fields.
  • No file count or page-count limit.

How to use it

  1. 1
    Add your PDFs

    Click the upload area or drag in multiple PDF files. You can keep adding more after the first batch.

  2. 2
    Reorder if needed

    Use the up/down arrows next to each filename to set the page order in the merged output.

  3. 3
    Merge and download

    Click 'Merge PDFs'. The combined file appears with a download button — your originals are untouched.

Common use cases

  • Combining a cover letter and resume into one PDF for job applications.
  • Joining scanned invoices or receipts for an expense report.
  • Stitching together chapters or sections of a long document.
  • Bundling a contract with its appendices and exhibits.
  • Merging exported pages of a tax return.
  • Combining handouts before sharing with a class or team.

Tips for best results

Reorder before merging

It's much faster to set the right order with the up/down arrows now than to re-split and re-merge later.

Remove blank pages first

Use our Split PDF tool to drop pages you don't want, then merge — the result is cleaner.

Keep file sizes reasonable

Very large PDFs (hundreds of MB) consume significant memory. On mobile, merge in smaller batches if your device struggles.

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Frequently asked questions

Is there a file count limit?

No fixed limit. Practical ceiling is your device RAM — usually 50+ medium PDFs work fine.

Are my PDFs uploaded?

No. Merging happens in your browser using pdf-lib.