Firefox addon

. Tamper Data: This is one of the most used Addons for Pentesters, who traditionally make use of it for viewing and modifying HTTP/HTTPS headers and post parameters, trace and time HTTP response or requests, security test web applications by modifying POST parameters and a lot more. The add-on can be downloaded here.

Hack Bar: Another well known and very often used tool, it is mostly used for security audit , and comes strongly recommended for installation and XSS, SQL Encoding/Decoding - MD5, SH1, Base64, Hexing, Splitting etc. The add-on can be downloaded here.
Live HTTP Headers: Similar to the Tamper Data add-on, the one big difference this add-on has is that it allows for viewing HTTP headers of a page while browsing. The add-on can be downloaded here.
User Agent Switcher: This particular add-on works wonders in adding a menu and a toolbar button to switch the user agent of a browser. This is, in turn, helpful in the changing of a User Agent to IE, Search Robots, I-Phone (I-OS). Besides this, the user can also use this add-on in the creation of his or her own User Agent. The add-on can be downloaded here.
Cookie Manager+: This is a great add-on for viewing, editing, creating and injecting cookies. The best thing about the add-on is the fact that it displays extra information about cookies, allows edit multiple cookies at once & backup/restore. The add-on can be downloaded here.
HTTP Fox: This add-on works for those looking to monitor and analysing all incoming and outgoing HTTP traffic between the browser and the web servers. The aim of the add-on is to bring the functionality known from tools like Http Watch or IE Inspector to the Firefox browser. The add-on can be downloaded here.
Passive Recon: This add-on gives its users the capability of performing "packetless" discovery of target resources utilizing publicly available information. The add-on can be downloaded here.

8.SQL Inject me :SQL Injection vulnerabilites can cause a lot of damage to a web application. A malicious user can possibly view records, delete records, drop tables or gain access to your server. SQL Inject-Me is Firefox Extension used to test for SQL Injection vulnerabilities.The add-on can be downloaded here.