What are some alternatives?
When comparing Crawl Center and A1 Website Analyzer, you can also consider the following products
Screaming Frog SEO Spider - The Screaming Frog SEO Spider is a small desktop program (PC or Mac) which crawls websites’ links...
SiteData.co - Website Analysis Tools
Pulno - SEO Audit and Website Analysis. Pull up your SEO.
Integrity - Feature comparison of link checkers for Mac: Integrity, Integrity Plus and Scrutiny
ContentKing - The world's only Real-time SEO Auditing and Content Change Tracking suite.
LinkChecker - LinkChecker is a free, GPL licensed website validator.