OWASP : The Open Web Application Security Project (OWASP) is a worldwide not-for-profit charitable organization focused on improving the security of software.
The Big List of Naughty Strings : The Big List of Naughty Strings is a list of strings which have a high probability of causing issues when used as user-input data.
Stack Overflow : Stack Overflow is a question and answer site for professional and enthusiast programmers.