Tools

Reconnaissance

Maltego An active tool to discover company data
Recon-ng A modular framework to identify IP addresses, locations, and people
The Harvester A tool to find company email addresses
Gitrob A passive tool to search Github for confidential data
DNSEnum A perl script to enumerate DNS info and discover non-contiguous IP blocks

Network Analysis

Wireshark A network packet sniffer and analyser.
Nmap Used to Scan Ports and Map Networks for network discovery and security auditing

Disassemblers

IDAPro Industry standard multi-processor disassembler and debugger
JD GUI A Java decompiler which can decompile and analyze Java 5 “byte code” and the later versions
OllyDgb A 32-bit assembler level analysing debugger for Microsoft® Windows®
Uncompyle2 A Python 2.7 byte code decompiler

Hex Editors

0xED (OSX) a native OS X hex editor based on the Cocoa framework
Hex Fiend A fast and clever open source hex editor for Mac OS X
HxD A carefully designed and fast hex editor which, additionally to raw disk editing and modifying of main memory (RAM), handles files of any size
Hexplorer Binary (hexadecimal) editor for Windows

Web Exploitation

Burp Suite An intercepting proxy
ntoinsight and ntoweb A is the industry-leading vulnerability management solution
XSS Cheatsheet A go to reference for XSS examples and explanations