Acunetix is described as 'Audit your website security and web applications for SQL injection, Cross site scripting and other web vulnerabilities with Acunetix Web Security Scanner. Download Free Edition!' and is a vulnerability scanner in the security & privacy category. There are more than 50 alternatives to Acunetix for a variety of platforms, including Web-based, Wordpress, Linux, Windows and Self-Hosted apps. The best Acunetix alternative is SiteOne Crawler, which is both free and Open Source. Other great apps like Acunetix are Burp Suite, Zed Attack Proxy (ZAP), OpenVAS and Nessus.
Burp Suite is for forced browsing whereas acunetix is finding vulnerabilities.