Opera 21 is a web browser developed by Opera Software ASA, available for download in full install version for Windows platforms from legacy sources. This version of Opera was officially released on 2014-05-06 for public access and a brief summary of important updates and change log pertaining to this edition can be read below.

Opera 21 has been built on Chromium 34 rendering engine using JavaScript engine V8. This version is supported in Windows XP and later versions except Windows 10.

With release of version 21, Opera team has extended support for Chromium's new UI frame work Aura for new design. With this version users can enjoy network installations without need to download the Opera browser setup file. Also one-click installation is now possible for extensions.

Among the security fixes, Opera notifies the user with a broken padlock for sites which have invalid security certificates. With advanced settings now user can view sites full URL in the URL window always. As usual the developers extended support for the latest Chromium/Blink release version 34.