Viper Browser is a free and open source lightweight privacy focused web browser for Linux. It is based on Qt framework and released under GPLv3 license. It is a new project and still in active development. It comes with buil-in ad blocking with easylist, easy privacy, uBlock filters and AdBlock Plus filters. And you can also add any custom filters. You can set startpage, searx, Google and duckduckgo search engines as default.
Some other features are auto fill manager, tab hibernation and wake up, embedded PDF.js support, UserScript support, custom user agent support, pepper plugin API support, bookmark management, cookie viewer and editor and cookie filters support.