OIMG review
A free, open-source compressor for metric-driven image optimization across desktop platforms.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
OIMG is an open-source desktop image compressor for people who want local control over image optimization. It supports Windows, macOS, and Linux, with workflows for both lossy and lossless compression. Its audience includes developers, designers, content teams, and technically minded users who need to compare output quality while reducing image size. Support for PNG, JPEG, WebP, AVIF, and JPEG XL gives it a modern format range, while command-line operation extends it beyond a desktop-only workflow.
Pricing is straightforward: OIMG is free for personal and academic use, and the product is open source under GPLv3. Commercial use is handled through custom licensing arrangements rather than a published paid tier. That makes the product easier to evaluate for individual projects, academic work, and teams that can operate within the stated free-use terms. Organizations planning commercial deployment should review licensing with OIMG before adopting it as part of a production process.
The standout feature is its measurement-led comparison workflow. OIMG provides real-time Pixel Match Percentage, MS-SSIM, and SSIMULACRA 2 metrics, alongside original-versus-optimized comparison and image-difference visualization. These tools give users several ways to judge whether compression changes are acceptable instead of relying only on file size. Multithreading and SIMD optimizations support the processing workflow, while file-explorer shortcuts, one-click JPG or PNG conversion, and command-line operation accommodate different working styles. Choose OIMG if local processing, open-source access, modern formats, and measurable quality comparisons matter. Consider another tool if you need a broad commercial licensing program or an image workflow outside its supported desktop platforms and formats.
OIMG pros and cons
- Where it wins
- Supports both lossy and lossless compression across modern formats
- Shows Pixel Match, MS-SSIM, and SSIMULACRA 2 metrics in real time
- Works across Windows, macOS, Linux, CLI, and file-explorer workflows
- Where it doesn't
- Free use is limited to personal and academic purposes
- Commercial licensing requires a custom licensing arrangement
- The workflow is focused on PNG, JPEG, WebP, AVIF, and JPEG XL
OIMG fact sheet, pricing and score →
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