Cross-Origin Resource Sharing (CORS) https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS What requests use CORS? This cross-origin sharing standard can enable cross-site HTTP requests for: Web Fonts (for cross-domain font usage in @font-face within CSS), so that servers can deploy TrueType fonts that can only be loaded cross-site and used by web sites that are permitted to do so. WebGL textures. Images/video frames drawn to a canvas using drawImage(). CSS Shapes from images. Simple Requests Some requests don’t trigger a CORS preflight.