The Open Web Application Security Project
OWASP is a nonprofit organization dedicated to improving the security of software with hundreds of local chapters and tens of thousands of members worldwide.
As the source for developers and technologists to secure the web, the foundation offers:
Application security tools and standards.
Complete books on application security testing and secure code.
Development and secure code review.
Presentations and videos.
Cheat sheets.
Standard security controls and libraries.
Local chapters worldwide.
Cutting-edge research.
Global conferences.
Mailing lists.