Hackbar for Firefox gives web developers the opportunity to test the security of their own code quickly and easily. This makes even the most complicated URLs readable for those who know what they are doing. Once the URL is executed, you can resume typing within the text area. Redirects have no impact on the text areas. Uu/url decoding and other useful tools are included. It also offers shortcuts for Oracle, MySQL, and MS SQL Server, as well as hashing for MD5/SHA1/SHA256.
Note that this add-on is designed for developers who understand how to make use of its functionality. It is not a teaching tool, so those who are inexperienced in coding and testing website security will need additional resources to be able to use it effectively.