I need a chrome or Firefox add on (or other method) to determine when the content I am viewing is loaded from Local browser cache or from the web server. Preferably breaking down each item as an image may be cached while other content on the same page may be from the server depending on expiry times and other headers.
As Geezer68 mentioned, you can use the Chrome Developer tools. Specifically, use the Javascript Console's Network tab and view the Size field which will specify (from cache) when the browser cache returns the content requested.