flipdf

Merge duplex-scanned PDFs into proper page order — for home scanners without auto-duplex.

Why?

Many home multifunction printers (like the Brother MFC-7460DN) have ADF (Auto Document Feeder) for continuous scanning, but lack automatic duplex scanning. This means scanning double-sided documents requires:

1. Scan all front pages → fronts.pdf
2. Flip the stack, scan all back pages → backs.pdf (pages come out in reverse order)
3. Manually interleave them... 😩

flipdf automates step 3. Just run flipdf in your scan folder and you're done.

Installation

Homebrew (macOS)

brew tap M-Igashi/tap
brew install flipdf

From Source

git clone https://github.com/M-Igashi/flipdf.git
cd flipdf
cargo install --path .

Usage

Automatic Mode (Recommended)

Just navigate to your scan folder and run:

flipdf

flipdf will automatically detect the two newest PDFs and merge them. The older PDF is treated as fronts, the newer as backs (since you scan fronts first, then flip and scan backs).

Explicit Mode

Specify files directly:

flipdf fronts.pdf backs.pdf
flipdf fronts.pdf backs.pdf -o document.pdf

List PDFs

See what's in the current directory:

flipdf list
flipdf list --all

Options

Examples

# Basic: auto-detect and merge
flipdf

# With cover page
flipdf --prepend cover.pdf

# Explicit files with custom output
flipdf fronts.pdf backs.pdf -o contract.pdf

# Add both cover and appendix
flipdf fronts.pdf backs.pdf --prepend cover.pdf --append appendix.pdf

# Check what would be merged
flipdf --dry-run

How It Works

When you scan a duplex document without auto-duplex:

Original document:  [1] [2] [3] [4] [5] [6]
                     ↓   ↓   ↓   ↓   ↓   ↓
                    F1  B1  F2  B2  F3  B3  (F=front, B=back)

Scan fronts (ADF):  F1, F2, F3 → fronts.pdf (pages 1,2,3)

Flip stack & scan:  B3, B2, B1 → backs.pdf (pages 1,2,3 = original B3,B2,B1)

flipdf merges:      F1, B1, F2, B2, F3, B3 → merged.pdf (correct order!)

License

MIT