firemark

A fast, single-binary watermarking tool for images and PDFs. Built in Rust.

Why watermark your documents?

Every year, millions of people fall victim to identity fraud that starts with a simple document exchange. A common scenario: you're looking for a flat to rent. The landlord — or someone posing as one — asks for a copy of your ID, a pay stub, a tax notice. You send them unmarked. The "landlord" disappears, and your documents are now used to open bank accounts, take out loans, or forge identities in your name.

Watermarking every document you send out is the single most effective defence. A visible overlay that reads "Sent to XYZ agency — March 2026 — flat rental application only" makes the document useless for any other purpose. If it leaks, you know exactly where it came from.

firemark makes this effortless: one command, any image or PDF, 17 visual styles, cryptographic filigrane patterns that resist editing, and batch processing for entire folders.

Before and after — one command, document is now traceable and tamper-evident.

Install

From crates.io:

cargo install firemark

From source:

git clone https://github.com/Vitruves/firemark.git
cd firemark
cargo install --path .

Produces a single optimized binary (~5 MB).

Quick start

# Watermark a single image
firemark photo_id.png -m "Flat rental — SCI Dupont — March 2026"

# Watermark a PDF
firemark tax_notice.pdf -m "CONFIDENTIAL" -s "Do not distribute"

# Watermark an entire folder recursively
firemark ./documents/ -R -m "Sent to Agency X" -t stamp

# Preview without writing files
firemark id_card.jpg -m "Draft" -n

Output is saved alongside the input as {name}-watermarked.{ext} by default. Use -o to set an explicit output path, or -S for a custom suffix.

Watermark types

firemark doc.pdf -t stamp -m "CONFIDENTIAL" --border --color red

Security filigrane

firemark overlays cryptographic filigrane patterns inspired by banknote security features. These fine geometric patterns are extremely difficult to remove with image editors.

firemark id.png -m "Rental application" --filigrane moire
firemark id.png -m "Rental application" --filigrane none   # disable

AI-removal hardening

Every render is non-deterministic by default. firemark applies universal post-render perturbation (alpha jitter, sub-pixel color noise, edge micro-dots, sparse ghost pixels) and per-renderer randomization so that no two outputs are pixel-identical — even with the same settings. This makes it impossible for AI vision models to learn a predictable pattern to subtract.

On top of that, adversarial prompt-injection strips are embedded by default to confuse AI watermark removal tools. Disable with --no-anti-ai if you don't want the visible prompt text:

firemark doc.png -m "CONFIDENTIAL" --no-anti-ai

Common options

-m, --main-text           Primary watermark text
-s, --secondary-text      Secondary text line
-t, --type                Watermark style (see table above)
-o, --output              Output file path
-S, --suffix              Custom output suffix (default: "watermarked")
-c, --color               Color — name or #RRGGBB (default: blue)
-O, --opacity             Opacity 0.0–1.0 (default: 0.5)
-r, --rotation            Angle in degrees (default: -45)
-p, --position            center, top-left, top-right, bottom-left, bottom-right, tile
-f, --font                Font name or path to .ttf/.otf
-I, --image               Overlay an image as watermark
    --qr-data             Embed a QR code with custom data
    --qr-code-position    QR code placement (default: center)
    --qr-code-size        QR code size in pixels (default: auto)
    --border              Draw a border around the watermark
    --shadow              Add a drop shadow
    --filigrane           Security filigrane style (default: guilloche)
    --no-anti-ai          Disable adversarial prompt injection (on by default)

For the full list of 70+ flags, see CLI.md.

PDF options

    --pages           Pages to watermark (e.g. 1,3-5 or "all")
    --skip-pages      Pages to skip
    --behind          Place watermark behind content
    --no-flatten      Keep layers separate (flattened by default)
    --dpi             Render resolution (default: 150)

Batch processing

# Process all images and PDFs in a folder
firemark ./inbox/ -m "INTERNAL" -t tile

# Recursive, 8 threads, custom suffix
firemark ./docs/ -R -j 8 -m "Draft" -S draft

# Dry run — list what would be processed
firemark ./docs/ -R -m "Draft" -n

Already-watermarked files (matching the suffix) are automatically skipped on re-runs.

Configuration file

Save options in a TOML file to avoid repeating flags. See examples/config/firemark.toml for a full example with two presets: ultra-secure (dense tiling, full filigrane, QR traceability, metadata stripping) and light (simple diagonal text, no extras).

# Global defaults
main_text = "CONFIDENTIAL"
secondary_text = "{author} — {date}"
watermark_type = "diagonal"
color = "#1a3c6e"
opacity = 0.45
font_weight = "bold"
filigrane = "guilloche"
border = true

[preset.ultra-secure]
main_text = "CONFIDENTIAL — {author}"
watermark_type = "tile"
color = "#CC0000"
opacity = 0.6
filigrane = "full"
anti_ai = true
qr_data = "firemark://{author}/{timestamp}/{uuid}"
strip_metadata = true

[preset.light]
main_text = "COPY"
watermark_type = "diagonal"
color = "#555555"
opacity = 0.3
filigrane = "none"
anti_ai = false

firemark doc.pdf --config firemark.toml
firemark doc.pdf --config firemark.toml --preset ultra-secure
firemark doc.pdf --config firemark.toml --preset light
firemark doc.pdf --save-preset mypreset    # save current flags
firemark --list-presets                     # list available presets

Format support

Cross-format conversion is supported (e.g. firemark photo.webp -o out.pdf).

License

MIT