What are some alternatives?
SEO Crawler - A web-based crawler with real-time crawl feedback.
Netpeak Spider - A desktop tool for fast and comprehensive technical audit of the entire website.
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.
ContentKing - The world's only Real-time SEO Auditing and Content Change Tracking suite.
Pulno - SEO Audit and Website Analysis. Pull up your SEO.
Seodity - The complete SEO toolkit for improving your projects.