Although there are many Open Source Web Application Security Scanners and they have some similar functions, we should choose the best of them. In this paper we have compared and assessed a list of Open Source Web Application Security Scanners with a focus on OWASP Top 10-2013 application security risks. One of the significant results of this research is that W3AF 1.2, arachniv0.4.0.3 and Skipfish 2.07 are the best of our sample. We showed the difference between Open Source Scanners concentrated on Injection, Cross- Site Scripting and Broken Authentication and Session Management.