Interesting that most of their showcase apps are antivirus apps.

Not a surprise actually as AV software:

1. shall not be CPU consuming. That famous 13% CPU consumption on blinking caret (https://github.com/Microsoft/vscode/issues/22900) is not acceptable.

2. shall be as compact as possible.

3. shall follow modern UI trends on the long run and without major code refactoring. See: 10 years of UI evolution of Norton 360: https://sciter.com/from-skeuomorph-to-flat-ui-evolution-of-o... with Sciter.

4. Shall support Section 508 / Accessibility as they used by governments and in official institutions.

5. Shall support flexible layouts and screen sizes used in the wild. UI nailed down to pixel grids in light of high-DPI Retina's is not an option anymore. Sciter UIs work on 500 mln PCs and Macs and counting.

6. UI these days shall be GPU accelerated, Retina has 9 times more pixels than 96ppi "classic" screens.

7. Code-behind-UI shall be flexible and GCable as UI objects ownership graph is complex and may contain loops: "on-this-button-click-hide-that-and-expand-those-and-disable-the-button-until-done".

8. Shall support multiple languages and adjust layout to them: https://sciter.com/images/wt-langs.png

All that...

I've found that antivirus in general (apart from their bad security practices) consistently fails at multiple of those points. For example:

Consumes a lot of resources.

Fails to follow design guidelines of the platform, but then again, maybe "modern trends" are more important than following the design language of the platform ¯\_(ツ)_/¯

Disclosure: c-smile is the author of sciter.

You know, I wouldn't be surprised if most Anti-virus applications nowadays were basically the same core software but each with a few different kinds of frosting on top...

That has dependencies on the UI toolkits, judging by the binary names (gtk dependency).