pdftk-server

What this skill does

# PDFtk Server

PDFtk Server is a command-line tool for working with PDF documents. It can merge, split, rotate, encrypt, decrypt, watermark, stamp, fill forms, extract metadata, and manipulate PDFs in a variety of ways.

## When to Use This Skill

- Merging or joining multiple PDF files into one
- Splitting or bursting a PDF into individual pages
- Rotating PDF pages
- Encrypting or decrypting PDF files
- Filling PDF form fields from FDF/XFDF data
- Applying background watermarks or foreground stamps
- Extracting PDF metadata, bookmarks, or form field information
- Repairing corrupted PDF files
- Attaching or extracting files embedded in PDFs
- Removing specific pages from a PDF
- Collating separately scanned even/odd pages
- Compressing or decompressing PDF page streams

## Prerequisites

- PDFtk Server must be installed on the system
  - **Windows**: `winget install --id PDFLabs.PDFtk.Server`
  - **macOS**: `brew install pdftk-java`
  - **Linux (Debian/Ubuntu)**: `sudo apt-get install pdftk`
  - **Linux (Red Hat/Fedora)**: `sudo dnf install pdftk`
- Access to a terminal or command prompt
- Verify installation by running `pdftk --version`

## Step-by-Step Workflows

### Merge Multiple PDFs

```bash
pdftk file1.pdf file2.pdf cat output merged.pdf
```

Using handles for more control:

```bash
pdftk A=file1.pdf B=file2.pdf cat A B output merged.pdf
```

### Split a PDF into Individual Pages

```bash
pdftk input.pdf burst
```

### Extract Specific Pages

Extract pages 1-5 and 10-15:

```bash
pdftk input.pdf cat 1-5 10-15 output extracted.pdf
```

### Remove Specific Pages

Remove page 13:

```bash
pdftk input.pdf cat 1-12 14-end output output.pdf
```

### Rotate Pages

Rotate all pages 90 degrees clockwise:

```bash
pdftk input.pdf cat 1-endeast output rotated.pdf
```

### Encrypt a PDF

Set an owner password and a user password with 128-bit encryption (default):

```bash
pdftk input.pdf output secured.pdf owner_pw mypassword user_pw userpass
```

### Decrypt a PDF

Remove encryption using the known password:

```bash
pdftk secured.pdf input_pw mypassword output unsecured.pdf
```

### Fill a PDF Form

Populate form fields from an FDF file and flatten to prevent further edits:

```bash
pdftk form.pdf fill_form data.fdf output filled.pdf flatten
```

### Apply a Background Watermark

Place a single-page PDF behind every page of the input (input should have transparency):

```bash
pdftk input.pdf background watermark.pdf output watermarked.pdf
```

### Stamp an Overlay

Place a single-page PDF on top of every page of the input:

```bash
pdftk input.pdf stamp overlay.pdf output stamped.pdf
```

### Extract Metadata

Export bookmarks, page metrics, and document information:

```bash
pdftk input.pdf dump_data output metadata.txt
```

### Repair a Corrupted PDF

Pass a broken PDF through pdftk to attempt automatic repair:

```bash
pdftk broken.pdf output fixed.pdf
```

### Collate Scanned Pages

Interleave separately scanned even and odd pages:

```bash
pdftk A=even.pdf B=odd.pdf shuffle A B output collated.pdf
```

## Troubleshooting

| Issue | Solution |
|-------|----------|
| `pdftk` command not found | Verify installation; check that pdftk is in your system PATH |
| Cannot decrypt PDF | Ensure you are providing the correct owner or user password via `input_pw` |
| Output file is empty or corrupt | Check input file integrity; try running `pdftk input.pdf output repaired.pdf` first |
| Form fields not visible after fill | Use the `flatten` flag to merge fields into the page content |
| Watermark not appearing | Ensure the input PDF has transparent regions; use `stamp` for opaque overlays |
| Permission denied errors | Check file permissions on input and output paths |

## References

Bundled reference documents in the `references/` folder:

- [pdftk-man-page.md](references/pdftk-man-page.md) - Complete manual reference with all operations, options, and syntax
- [pdftk-cli-examples.md](references/pdftk-cli-examples.md) - Practical command-line examples for common tasks
- [download.md](references/download.md) - Installation and download instructions for all platforms
- [pdftk-server-license.md](references/pdftk-server-license.md) - PDFtk Server licensing information
- [third-party-materials.md](references/third-party-materials.md) - Third-party library licenses