Sielo has all the basic functionalities of a web browser (tabbed browsing, bookmark, history, private browsing, web browsing (yes it is possible), etc.) and even some advanced features such as an integrated AdBlock, proxy management, cache management, ability to save passwords (and encrypt them with a super password). Sielo uses the web engine WebEngine that comes with Qt. But that's not all, Sielo has also unique and original features:
Tabs space: This is the feature that makes Sielo so special. Tabs spaces allow you to divide your Sielo window into several spaces, as if you had several windows next to each other but interacting with each other. You can resize Tabs spaces, hide them, mute them... This allow you, among other things, to have several sessions, for example a session called "social networks", an other called "music" and an other called "work". Therefore you can hide the "music" tabs space and retrieve it at any time.
The floating button: This is another feature specific to Sielo.. This button can be moved everywhere in the browser to give you access to the main controls as easily as possible. It can also be transformed into a lateral toolbar.
Themes, for an unlimited personalization power: Sielo also supports themes to completely customize the interface. This goes from the floating button to the tabs, via icons. I'm currently writing a little tutorial to learn how to make themes for Sielo. This is not very complicated, just place the icons, list them in a file "theme.index" and do some CSS to customize some objects such as tabs. If the developer wants, the themes can behave differently depending on the operating system, and can be adapted with user colors.
NOTE: This is only to provide appimages, I am not the developer.