Cacao (CORS Access-Control-Allow-Origin) Proxy
The Cacao CORS Proxy Browser Extension intercepts the Fetch API for whitelisted URLs.
Find it on GitHub (http://github.com/michaelfig/cacao-extension)
The main application of Cacao is to allow Javascript running in a web browser to access cross-origin images (plain, or streams such as MJPEG) without failing due to Cross-Origin restrictions.
This is useful for applications such as WebRTC, which may need to process images from neither localhost nor the script's default origin.