You only need to have just basic knowledge of JavaScript in order to develop extensions. There is no need to be familiar with a lot of different technologies and programming languages.
Using Kango write single code which works in the same way with all major browsers: Firefox, Chrome, Internet Explorer, Safari, Opera.
Kango provides developer-friendly API increasing development rate by several times and easily resolving standard tasks (cross domain requests, browser interaction, etc.).
Add your own dynamically modifiable button to browser and HTML popup by just a couple of lines of code.
Kango provides full access to DOM and supports userscripts for alteration of page content. Adapt your userscript in matter of minutes.
Send queries to server, process data and do any other complex tasks in the background (asynchronously).