Developing browser extensions can be a daunting task. If you want to release a version of your extension for each major browser in the market, you basically have to develop a different extension for each one of them. Sometimes you'll be able to reuse code (e.g., between Chrome and Safari extensions), and sometimes not (e.g., between Firefox and IE extensions).
In order to simplify this task you can rely on a cross-browser extension development framework. With this choice you'll be able to release a working extension for all major browsers at the cost of having limited control over what your extension can do. This is what I call the Fast Way of developing a browser extension. You may read about other alternatives here.
Some of the most important cross-browser extension development frameworks are listed below:
- Kynetx supports IE, Firefox, Safari, and Chrome, but extensions are dependent on the Kynetx extension to work. In addition, Kynetx apps are built using a proprietary Kynetx Rules Language. There is no cost to use the Kynetx platform.
- CrossRider supports IE, Firefox, and Chrome. CrossRider is free and jQuery-based. Currently CrossRider does not allow you to self-host your plugins; they must be installed from CrossRider's website.
- KangoExtensions supports IE, Firefox, Chrome, Safari and Opera. Kango is only free for open source non-profitable projects.
- Conduit supports IE, Firefox, Safari, and Chrome. It enables you creating a branded, customized toolbar that offers users a direct interface or “Conduit” to the most valuable and important segments and links of your Blog or website. Conduit is free, easy to use and allows you to monetize your toolbar with a shared-profit revenue model. Since Conduit basically lets you link from a toolbar a portion of your web page, it inherently lacks from the flexibility of other cross-browser extension development frameworks.