The Firefox web browser maintains three different caches: The memory cache, the disk cache and the offline cache. It is possible to access those caches from within the browser by loading the about:cache page in the browser's address bar, or by opening the cache location on the computer's hard drive. The latter method is obviously not available for the memory cache.
The cache display on the internal Firefox page is not comfortable to work with. All entries are lumped together on one large page, and while they provide basic information like item size, date and url, they lack manageability. There are no sorting options and no options to search the cached items, other than pressing Ctrl-f to utilize Firefox's page search.
The default cache page has another weakness. It cannot be used to save files to the local hard drive.
Enter Cache Viewer Fx5, based on the original and discontinued Cache Viewer add-on.
Firefox users can access the extension's interface with a click on Tools > Cache Viewer or with the shortcut Ctrl-Shift-C.
The interface lists all cache items, regardless of location, in the lower half of the interface. Each item is listed with its key, size, mime type, device and the date the data was fetched. All columns are sortable to find specific items fast, for instance all images that have been loaded into the cache or all files from a specific domain.
A right-click on a single item or multiple items opens a context menu with options to save the selection to the local hard drive, to delete the items or to open them in the default web browser.
The footer bar displays the number of memory and disk cache entries, and a reload button to quickly reload the cache.
The upper half of the screen contains an image preview area on the left and detailed information about the selected file on the right. This includes the data that is shown in the list of cached items plus information like the server and request method, expiration time (great for webmasters to check the caching directives of their websites) or the ETAG code.
CacheViewer Fx5 adds much needed features to the Firefox web browser, specifically the ability to search, sort and save cache entries need to be mentioned.
Firefox users can install the add-on from the official Mozilla Firefox website. The add-on is compatible with all versions of the Firefox browser from 4 on.
Update: The original Cache Viewer extension reviewed here is no longer available. I suggest you try out CacheViewer2 instead, which offers a similar feature set and is still maintained by its author.
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