# 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 — what we do not do

This tool runs entirely in the browser via WebAssembly. Your file never reaches a Loft Tools server. Specifically:

- **No upload.** The file bytes load into the browser tab's memory and process on your own CPU. Open DevTools → Network and observe zero outbound requests carrying file data while Merge PDF Files runs.
- **No AI training on your file.** Loft does not train models. We could not train on a file we cannot see.
- **No content scanning.** No virus, copyright, or content-moderation pass against your file. The bytes are not accessible to us.
- **No server-side log of file contents, filenames, or EXIF metadata.** Cloudflare edge captures URL and truncated IP for abuse defense (standard CDN behaviour). Cloudflare Web Analytics records anonymous page hits, no cookies, no PII. Nothing about your file content reaches any log.
- **No retention.** Close the tab and the file leaves browser memory. No backups exist on our side because no copy ever existed on our side.
- **No account.** No email, no signup, no auth, no telemetry tied to you.
- **Offline-capable after first visit** (PWA). Once you've loaded a tool, it caches; later sessions work without internet. For high-sensitivity files, run the tool once online to warm the cache, then disconnect before processing.

Compare with upload-based services: each transmits your file to a processing server. Even over HTTPS, each has logs, retention windows, and subpoena exposure. Loft has none of these because the server architecture does not include your file.

## More

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