Opera

Opera is a proprietary web browser developed and maintained by a company of the same name. Opera became notable in the past for its strict adherence to web standards and its unique user interface, as well as its speed. In 2013, Opera's rendering engine, Presto, was removed in favor of WebKit (and soon after, Blink), used by Chrome. This, along with many other issues, has led to the abandonment of its userbase in fear that Opera has become a much weaker Chrome clone.

Opera
Type	Proprietary
Layout engine	Blink
Website	http://www.opera.com/

In 2017 Presto's source code was leaked to Github and soon taken down, a mirror of it is hosted on Gitlab.