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MozJPEG
What it is
MozJPEG is a free, open-source JPEG compression library intended for graphics programs and image-processing tools. It aims to improve compression efficiency while preserving visual quality, and is compatible with the JPEG standard and most deployed JPEG decoders. Applications that use the libjpeg API can integrate it without writing MozJPEG-specific integration code. Progressive encoding with jpegrescan optimization can losslessly reduce a JPEG when used with jpegtran; trellis quantization is used when converting other formats to JPEG. MozJPEG improvements can be turned off at runtime, after which it behaves like libjpeg-turbo. The repository includes a demo cjpeg command-line tool, which is not intended for serious use. Build instructions cover Unix-like systems, macOS, Linux, and Windows with Visual C++ or MinGW. The repository identifies version 4.1.1 as the latest release and points to libjpeg-turbo documentation for additional build help. The listed plan is free.
For and against
For
- Free, open-source JPEG library
- Compatible with the JPEG standard
- Integrates through the libjpeg API
- Progressive encoding can reduce JPEG size losslessly
- Improvements can be disabled at runtime
Against
- Demo cjpeg tool is not intended for serious use
- Build help points to libjpeg-turbo documentation
The verdict
MozJPEG is a free library for integrating JPEG compression improvements into graphics and image-processing software. The included command-line tool is only a demo, not intended for serious use.
Who it suits
MozJPEG suits developers building graphics software or image-processing tools who want a JPEG library compatible with the libjpeg API. Its build instructions cover multiple operating systems and build environments.
Plans and prices
MozJPEG
Open-source JPEG encoder library; demo cjpeg tool
Read 7 Oct 2026 · github.com
On the record
- API access
- Yesgithub.com · read 20 Sep 2026
- Build platforms
- The build instructions describe Unix-like systems, macOS, Linux, Windows with Visual C++, and Windows with MinGW.github.com · read 7 Oct 2026
- Command-line tool
- The repository includes a demo cjpeg command-line tool, which the project says is not intended for serious use.github.com · read 7 Oct 2026
- Compatibility
- It is compatible with the JPEG standard and the vast majority of deployed JPEG decoders.github.com · read 7 Oct 2026
- Compression modes
- bothgithub.com · read 20 Sep 2026
- Distribution
- The GitHub repository provides a latest release page, which identifies version 4.1.1 as the latest release.github.com · read 7 Oct 2026
- Integration
- Programs using the libjpeg API can integrate MozJPEG without writing MozJPEG-specific integration code.github.com · read 7 Oct 2026
- Library use
- The project is intended as a library for graphics programs and image processing tools.github.com · read 7 Oct 2026
- Metadata controls
- Yesgithub.com · read 20 Sep 2026
- Progressive encoding
- Progressive encoding with jpegrescan optimization can losslessly reduce the size of any JPEG when applied with jpegtran.github.com · read 7 Oct 2026
- Purpose
- MozJPEG improves JPEG compression efficiency to achieve smaller files and higher visual quality.github.com · read 7 Oct 2026
- Runtime behavior
- MozJPEG improvements can be disabled at runtime, in which case it behaves exactly like libjpeg-turbo.github.com · read 7 Oct 2026
- Security
- The repository page does not state security certifications or compliance claims.github.com · read 7 Oct 2026
- Support
- The project points users to libjpeg-turbo documentation for additional build help.github.com · read 7 Oct 2026
- Supported formats
- PPM,PGM,BMP,GIF,Targagithub.com · read 20 Sep 2026
- Trellis quantization
- Trellis quantization is used when converting other formats to JPEG to maximize the quality-to-file-size ratio.github.com · read 7 Oct 2026
