Whatsmyserp - Powerful Rank & Serp Tracking. Completely Free.
Dr. Link Check - Broken link checker with malware and parked domain detection
SEOmator - SEO website analysis & audit tool
LinkChecker - LinkChecker is a free, GPL licensed website validator.
Panguin Tool by Barracuda Digital - See your website's Google organic visit data overlaid with Google's major algorithm updates and changes to easily identify the impact on your website. Technology by Barracuda Digital.
BrokenLinkCheck - Free Broken Link Checker / Online Dead Link Checking Tool - find bad hyperlinks