I just found Tincr, and wanted to use it to watch a local HTML file. But when I tried to use it with a file:// URL, it failed to update. If I understood the documentation correctly, it should just work with file:// URLs without any configuration.
So, I checked the console for the background page, and found this:
Native file support successfully loaded nativeSupport.js:5
XMLHttpRequest cannot load file:///C:/Users/path/to/file.html?r=4383065. Cross origin requests are only supported for protocol schemes: http, data, chrome-extension, https, chrome-extension-resource. background.html:1
Uncaught NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'file:///C:/Users/path/to/file.html?r=4383065'. zepto1.0rc1.js:2
XMLHttpRequest cannot load file:///C:/Users/path/to/file.html?r=1873894. Cross origin requests are only supported for protocol schemes: http, data, chrome-extension, https, chrome-extension-resource. background.html:1
Uncaught NetworkError: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'file:///C:/Users/path/to/file.html?r=1873894'. zepto1.0rc1.js:2
Definitely strange errors. Not really a CORS request.
I'm using this on Chrome 38.0.2096.0 dev-m on Windows 7.