Chrome 79 brings some important changes in its CORS implementation, rolling out now, which mean that CORS preflight OPTIONS requests will no longer appear in the network tab of the Chrome developer tools. If it's allowed, the browser goes on to send the real request, if not then the application isn't allowed to make that request, so it fails. HTTP Toolkit lets you collect all traffic the browser sends, even for CORS requests (or any other requests) that happen outside the core renderer process.