Web Archive Viewer is an Opera add-on that help you easily see the cached version of any website.
This addon uses seven different engines to render the website's archive version. By default, three engines are selected, but you can add or remove them at any time via the option's page.
When you visit a page, simply open toolbar popup UI and then click on a desired archive engine. A new tab will be open to render the cached version of the current tab. Please note that, not all websites have a cached version. Moreover, depending on the archive engine that you choose the cached version might look different.
If you see any bug, or have a feature request in mind, please fill the bug report form at the addon's homepage (http://mybrowseraddon.com/web-archive-viewer.html).