AVIF is an acronym that stands for "AV1 Image File Format" and represents one way to store both still images and animated images compressed with AV1 in HEIF file format. AVIF offers extended color space capabilities (Wide Color Gamut, WCG) and features such as graininess, color undersampling, and HDR (High Dynamic Range). HDR is a technology that enables uniform brightness and solid colors and contrasts in images. HDR can be easily achieved with AVIF since it can go beyond the usual 8-bit color depth of standard dynamic range (SDR) images (up to 12-bit and higher color depths are possible). The metadata can be used to share HDR information and information concerning the color gamut. The ability to create animation sequences similar to GIF animations (Animated GIFs) is also available (support for multi-layer images for image elements and sequences).
In its own words, KeyCDN describes itself as a high-performance content delivery network designed for the future. It takes a few minutes to start delivering content to your users at a swift pace. Image processing is one of KeyCDN's specialties. Using image processing, images can be transformed and optimized on the fly. Real-time image processing allows their high-performance content delivery network to alter and enhance photos based on simple query parameters before delivery. Thus, your users will receive processed images with low latency regardless of their location.
To this date, KeyCDN does not support AVIF. It is unknown whether they will add support in the future.