ImageRatio Img Optmizer by RatioWorks

ImageRatio is a privacy-focused image optimization toolkit for Firefox.
Optimize images directly on your device while preserving visual quality and original resolution. ImageRatio is designed to reduce image file sizes without unnecessarily degrading image quality.
Features
Local image optimization — images remain on your device.
Visual-fidelity safeguards designed to reject overly aggressive compression.
Original resolution is preserved by default.
Batch image optimization.
JPEG, PNG and WebP workflows.
Website Image Audit for identifying oversized and inefficient page images.
Eco, Balanced and Maximum processing modes for controlling CPU usage.
Download optimized copies without replacing the originals.
Full ImageRatio Studio interface for larger optimization jobs.
Privacy Image optimization is performed locally. ImageRatio 1.0 does not upload your images to an ImageRatio server or cloud optimization service.
ImageRatio requests only the Firefox permissions necessary for its current functionality. Website image auditing occurs when the user explicitly requests an audit.
ImageRatio prioritizes image fidelity over maximum compression. If an optimization does not provide worthwhile savings while satisfying the selected quality safeguards, ImageRatio can retain the original instead.
Future versions may introduce optional cloud-storage and website publishing integrations. Those services are not part of ImageRatio 1.0.