# Merge PDF Files

> Drop the PDFs you want combined, drag-reorder them in the strip, click merge, save the result. Bookmarks from each source nest into a per-file outline group; colliding form-field names get a per-file suffix so values don't silently overwrite. The merge runs in your browser via pdf-lib — no upload, no signup, no per-file size limit beyond what your browser can hold in memory.


Live tool: https://lofttools.com/tools/pdf-tools/merge-pdf

Category: PDF & Documents


## What it does

- Drag-and-drop ordering of source PDFs in a thumbnail strip
- Bookmarks from each source nest into per-file outline groups
- Form-field name conflict resolution via per-file suffix
- Combined PDF uses the highest PDF version among inputs
- Annotations preserved on each source's page range
- Page rotation flags from sources carry through
- PDF/A flag preserved when all inputs are PDF/A
- pdf-lib backed, runs in the browser tab
- No artificial file count or size limit

## How it works

1. **Select PDFs** — Drag and drop multiple PDF files or click to browse
2. **Arrange order** — Drag to reorder files in your preferred sequence
3. **Download** — Click merge and download your combined PDF instantly

## FAQ

### How many PDFs can I merge at once?

You can merge up to 20 PDF files at once with a combined size of up to 100MB.

### Does this preserve bookmarks and form fields?

Yes. Each source PDF's bookmarks merge into the combined document under a per-file bookmark group. Form fields keep their values; duplicate field names get a per-file suffix.

### What PDF versions are supported?

PDF 1.0 through 2.0 can be merged. The combined PDF uses the highest version among the inputs.

## Privacy

This tool runs entirely in the browser. Files are not uploaded to a server. They never leave the user's device.

## More

- All tools: https://lofttools.com/tools
- Category: https://lofttools.com/tools/pdf-tools
- LLM index: https://lofttools.com/llms.txt