The best open source alternative to Adobe Lightroom is Darktable. If that doesn't suit you, we've compiled a ranked list of other open source Adobe Lightroom alternatives to help you find a suitable replacement. Other interesting open source alternative to Adobe Lightroom is RawTherapee.
Adobe Lightroom alternatives are mainly Photo Editing Software. Browse these if you want a narrower list of alternatives or looking for a specific functionality of Adobe Lightroom.
Open source photography workflow application for RAW development. Non-destructive editing, professional color management, and GPU acceleration for photographers.

darktable is a comprehensive open source photography workflow application designed specifically for photographers who demand professional-grade RAW processing capabilities. This powerful tool serves as both a virtual lighttable and darkroom, providing everything needed to manage, develop, and enhance digital photographs.
Key Features:
Built by photographers, for photographers, darktable understands real-world workflows and challenges. The development team includes active photographers who bring practical experience to the software's design and functionality.
The application excels at RAW development with a comprehensive set of tools for exposure correction, color grading, noise reduction, and creative enhancement. Whether you're a professional photographer or serious enthusiast, darktable provides the advanced features needed for high-quality image processing without the cost of proprietary alternatives.
Looking for open source alternatives to other popular services? Check out other posts in the alternatives series and openalternative.co, a directory of open source software with filters for tags and alternatives for easy browsing and discovery.
Free, cross-platform raw image processor with 32-bit floating point engine, advanced demosaicing algorithms, and professional-grade editing tools for photographers.

RawTherapee is a professional-grade raw photo processing system that delivers exceptional image quality without the price tag. Built on a 32-bit floating point processing engine, it offers non-destructive editing capabilities that preserve every detail of your original raw files.
Key Features:
The software excels at developing raw files from a broad range of digital cameras, making it perfect for both enthusiast photographers looking to expand their digital imaging knowledge and professional photographers who demand the highest quality results.
As free and open-source software, RawTherapee gives you complete freedom to use, modify, and distribute the program. The active community provides excellent support, documentation, and continuous improvements to help you master advanced photo processing techniques.