Rails 5.2 feature for managing image/file uploads. The talk recommends using it to generate multiple image output formats (e.g. WebP for Chrome) to reduce bytes delivered, though it requires detecting the client browser. Janko notes that Active Storage was released with Rails 5.0 with a similar philosophy to Shrine, and that it adopted Janko's image_processing gem (with mini_magick and libvips wrappers) as of Rails 6.0. Active Storage encodes processing steps into the derivative URL, a design Janko doesn't favor because the URL grows with processing logic and cannot always represent block-based processing. It also ships its own JavaScript for uploads.