 <p>This is semi - manual and it isn't an extension. So it may not really answer the OP's question, but it may suit some situations. It looks long but it's not complicated or difficult. You can do it for just images or all files.</p> <p>It overcomes all the ajax tricks. It should work with any project or version of Visual Studio.</p> <p><strong>Steps</strong></p> <ol> <li>Run the website in Chrome with debugging turned on (press <kbd>F12</kbd> before launching website)</li> <li>Completely exercise the website. Make it download everything that it will ever download.</li> <li>Go to the <strong>Network</strong> tab.</li> <li>On the file grid, Click on any of the images that appear in the list (doesn't matter which one). This will make all column headers but <strong>Name</strong> go away.</li> <li>Click on the <strong>Name</strong> column header, to sort ascending.</li> <li>Do <kbd>CTRL</kbd>+<kbd>A</kbd>, <kbd>CTRL</kbd>+<kbd>C</kbd> to copy all file names.</li> <li>Paste into a new Google spreadsheet (in google docs) into cell <strong>A2</strong>.</li> <li>Repeat steps 6 and 7 if for any reason it didn't copy all the file names. Scroll down.</li> <li>Go into your actual website images directory (or whatever directory you are interested in comparing) in a command prompt and issue <code>dir /b</code>. Copy this into the clipboard (mark function) and paste into cell <strong>B2</strong>.</li> <li>In cell <strong>C2</strong>, paste this formula <code>=not(isna(VLOOKUP(B2,$A$2:$A$TheBottomOfA,1,false)))</code>. Alter <strong>TheBottomOfA</strong> to be the last used row in column <strong>A</strong>.</li> <li>Copy the formula down for all your values in column <strong>B</strong>.</li> <li>In cell <strong>C1</strong>, type <strong>Is Used</strong>. In cell <strong>B1</strong>, type <strong>Name</strong>. Add a data filter on all the values in columns B and C. Set the filter with the mouse in <strong>C1</strong> to show only <strong>Is Used</strong>=FALSE.</li> </ol> <p><strong>Result</strong></p> <p>What you're looking at in Column <strong>B</strong> is a list of files you are not using.</p> <p><strong>Note</strong></p> <p>I recommend moving the unused files to an offline folder instead of deleting them.</p> <p><strong>Warning</strong></p> <p>You still need to use common sense. <code>BRAIN=ON</code></p>