Web browsers have a major influence over the web pages rendering mode. As a consequence, in web design, the testing phase of a certain project against multiple web browsers is very important in order to repair possible bugs or incorrect page rendering issues.

There are many standalone tools or extensions specific to a certain browser type that permits you to verify a website compliance across different browsers, search engine optimization level, the degree of accessibility and usability of a given project and more.

For Mozilla Firefox web browser various add-ons or extensions related to web design projects development and testing are available. Many of the existing extensions could not interest advanced users, due to their disadvantages induced by the value of the ratio between usability, features and graphical user interface functionality. Among the large number of Firefox extensions made to simplify the work of both web designers as well as web programmers, there are a few add-ons used on a large scale, due to their efficiency.

MeasureIt is a Firefox add-on which automatically calculates width, hight or the degree of alignment for various web page elements with the help of a ruler. A related add-on, GridFox will help you in the creation of grid based sites by allowing you to overlay a grid on any web site. GridFox will also allow you to determine the alignment of web page objects with the precision of pixels level.

The problems related to web pages elements' color can be managed by installing ColorZilla and respectively Color Contrast Analyser extensions. ColorZilla allows you to determine or select the color codes used in a web page. Color Contrast Analyser will provide you a report that will help you to decide if the color scheme used in a certain web page has enough contrast between background and foreground colors in case of text. Another useful add-on, IE Tab will show the degree of compatibility of a web page with Internet Explorer browser directly from Firefox.

The add-ons presented in this article come as a complementary tool in your web design work. In any moment, the web design related Firefox add-on list could be completed, but these simple tools should improve the efficiency of websites development and testing by reducing the average work time and eliminating the need of complex or expensive software.