The best open source alternative to Affinity Photo is Darktable. If that doesn't suit you, we've compiled a ranked list of other open source Affinity Photo alternatives to help you find a suitable replacement. Other interesting open source alternatives to Affinity Photo are: GIMP and RawTherapee.
Affinity Photo alternatives are mainly Photo Editing Software but may also be Design & Prototyping Tools. Browse these if you want a narrower list of alternatives or looking for a specific functionality of Affinity Photo.
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, open-source image editor with professional tools for photo manipulation, digital art creation, and graphic design. Cross-platform support.

GIMP is a powerful, free alternative to expensive image editing software that delivers professional-grade results. This cross-platform editor runs seamlessly on GNU/Linux, macOS, Windows, and other operating systems, making it accessible to everyone.
Perfect for multiple creative disciplines: Whether you're a graphic designer crafting logos, a photographer retouching portraits, an illustrator creating digital art, or a scientist processing research images, GIMP provides sophisticated tools to match your workflow.
Key capabilities include:
Professional workflow integration features top-notch color management for consistent reproduction across digital and print media. The software integrates beautifully with other open-source tools in desktop publishing workflows.
Extensive customization through plugins, scripts, and community-created extensions means you can tailor GIMP to your specific needs. The active development community continuously adds new features and improvements, ensuring this free tool stays competitive with premium alternatives.
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.