Tool For: Those lazy web developers who want to easily have major control over the content that is displayed, sent, or received while browsing with Firefox.

This toolbar almost allows you to do anything and everything while browsing web sites through its quick and easy to use drop down selector boxes.

Disable: Allows you disable many items from cookies to javascript

CSS: Add, edit, or view stylesheets.

Forms: Convert from POST to GET or vice versa. Other options from auto completion to making passwords viewable.

Images: Display image paths and dimensions or just hide images altogether.

Information: View response headers to ID and class details.

Miscellaneous: Clear browser cache to zoom in/out.

Outline: Outline table cells to block elements

Resize: Display current size dimensions

Validate: Enables you to validate anything from css to the active document.

View Source: Quick click to view the source code of the current page.

Get tool here : Web Developer - Firefox Extension