This freeware Firefox add-on helps Web site administrators easily test page post and header data exchange.
Tamper Data acts as a stop sign between data exchanged from a Web site and your browser. For each subsequent request, the utility pops up a dialog to poll the user to tamper with the data, submit it as normal, or cancel the request. Users edit the data as they see fit and click to send it to the Web site, even you can fire SQL injections into website or you can modify cookies.
