- understanding-viewport 585 A set of simple HTML pages with various viewport and media query settings, for educational purposes
- pagespeed-ext 4 Simple PageSpeed Insights extension
- simple-demo 4
- Layers-Opera-extension 3 Generates a topographic view of any web page and visualizes how its different elements are layered on top of each other.
- shinydemos 3 Shiny Demos is a growing set of demos of the latest Open Web Standards, made by the Opera developer relations team.