cbz-tools-optimizer

High-performance CBZ optimizer built in Rust — batch resize, compress, and convert images (JPEG/PNG/WebP/AVIF) for Kindle and e-readers, fully offline.
CLI for Windows / Linux / macOS. Windows GUI included.

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Download

Download the latest release from Releases.

Archive	Contents
cbz-tools-optimizer-vX.Y.Z-windows-x64.zip	cbz-opt.exe (CLI) + cbz-opt-gui.exe (GUI)
cbz-tools-optimizer-vX.Y.Z-linux-x64.tar.gz	cbz-opt (CLI)
cbz-tools-optimizer-vX.Y.Z-macos-x64.tar.gz	cbz-opt (CLI)

Extract the archive and run the binary directly — no installation required.

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Why cbz-tools-optimizer?

📦 Storage savings	Significantly reduce file size — real-world result: 9.0 GB → 647.6 MB (-93%) in 1m 35s
🔄 Format conversion	Convert JPEG / PNG / WebP / AVIF in bulk — resize and convert in a single pass
⚡ Speed	Parallel processing across ZIPs and images via rayon
🖥️ Cross-platform	Windows / Linux / macOS — single binary, no install
🎯 Device-ready presets	iPad, Kindle, 4K and more — one flag to optimize for your device
🤖 Script-friendly	Batch CLI with JSON output for automation and pipeline integration
🖱️ GUI included	Windows drag-and-drop GUI — no CLI knowledge required

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CLI Usage

Resize

# Basic (default: ipad preset 2048×1536, JPEG quality 85)
cbz-opt input.cbz

# Multiple files
cbz-opt *.zip

# Kindle preset
cbz-opt --preset kindle --quality 80 --suffix _small *.cbz

# Custom size
cbz-opt --preset custom --max-width 1280 --max-height 720 input.zip

# Specify output directory
cbz-opt --output-dir ./output input.cbz

Format Conversion

# Convert all images to WebP (no resize)
cbz-opt --output-format webp --convert-only input.cbz

# Convert to AVIF for maximum compression (no resize)
cbz-opt --output-format avif --convert-only *.cbz

# Resize AND convert to WebP in one pass
cbz-opt --preset ipad --output-format webp input.cbz

# Convert PNG to JPEG (no resize)
cbz-opt --output-format jpeg --convert-only input.cbz

--convert-only: skips resizing entirely. Same-format files are passed through without re-encoding — zero quality loss.

Options

Option	Default	Description
--preset	ipad	Size preset (see table below)
-W, --max-width	—	Maximum width in pixels (--preset custom only)
-H, --max-height	—	Maximum height in pixels (--preset custom only)
-q, --quality	85	JPEG quality (1–100) — used when --output-format jpeg, or original without --convert-only (JPEG inputs may be re-encoded)
-s, --suffix	_new	Output filename suffix
-o, --output-dir	(same as input)	Output directory
-t, --threads	0 (auto)	Number of threads (0 = half of logical CPUs)
--output-format	jpeg	Output image format: jpeg / png / webp / avif / original
--convert-only	—	Convert format only — skip resize entirely. --preset / -W / -H are ignored. Same-format files are passed through without re-encoding (zero degradation)
--log-mode	cli	Log output: cli / silent / both / file
--overwrite-mode	skip	Output conflict resolution: skip / overwrite / rename
--json	—	Output progress as JSON lines (for scripting and automation)

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Size Presets

Preset	Width	Height	Intended device
ipad	2048	1536	iPad (default)
ipad-air	2360	1640	iPad Air
ipad-pro	2732	2048	iPad Pro
kindle	1264	1680	Kindle Paperwhite
hd	1280	720	HD display
full-hd	1920	1080	Full HD display
four-k	3840	2160	4K display
custom	(manual)	(manual)	Use -W / -H

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Supported Formats

Format	Input	Output
JPEG	Yes	Yes
PNG	Yes	Yes
WebP (static)	Yes	Yes
WebP (animated)	Detected, skipped	—
AVIF	—	Yes
BMP	Yes	Converted to output format
TIFF	Yes	Converted to output format
GIF	Skipped	—

Archives containing animated WebP or GIF are skipped entirely to preserve animations.
BMP and TIFF inputs are converted to the format specified by --output-format (default: jpeg).
AVIF is supported as output only (--output-format avif). AVIF files inside a ZIP are passed through unchanged.

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GUI Usage

1. Launch cbz-opt-gui.exe
2. Drag and drop ZIP/CBZ files or folders onto the window (or use Add Files… / Add Folder…)
3. Configure options via the ⚙ button and click ▶ Start
4. A completion summary is shown next to the Start button when processing finishes

Ready	Done

Notes:

• cbz-opt.exe is not required alongside the GUI — image processing is built in
• Supports English / 中文 / 日本語 (language selector in the menu bar)
• Settings are saved automatically to cbz-opt-gui.toml in the same folder

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Build from Source

Prerequisites (Windows): Requires the MSVC toolchain (stable-x86_64-pc-windows-msvc).
Install "Desktop development with C++" workload from Visual Studio 2022 (or Build Tools for Visual Studio).
The MSVC linker path is pre-configured in .cargo/config.toml — no Developer Command Prompt is required.

# All crates
cargo build --release

# CLI only  →  produces cbz-opt(.exe)
cargo build --release -p cbz-tools-optimizer-cli

# GUI only (Windows)  →  produces cbz-opt-gui.exe
cargo build --release -p cbz-tools-optimizer-gui

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Contributing

Bug reports and feature requests are welcome via GitHub Issues.
Please use the provided issue templates.

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How It Works

Multiple ZIP/CBZ files
  └── rayon::par_iter()   ← parallel across ZIPs
        └── each ZIP entry
              └── rayon::par_iter()   ← parallel across images
                    └── resize / convert with CatmullRom filter

• Images already within the size limit are passed through without re-encoding
• Each ZIP is processed independently; one failure does not abort others
• Default thread count is half of logical CPUs to avoid saturating the system (override with --threads N)
• Output file conflict is controlled by --overwrite-mode (default: skip existing files)
• A log file (cbz-opt_YYYYMMDD_HHMMSS.log) is written when --log-mode both or file is specified
• On completion, total file size savings and elapsed time are reported

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Changelog

See CHANGELOG.md.

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Third-Party Licenses

See THIRD-PARTY-LICENSES.md.

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License

MIT — see LICENSE.