Netpeak Spider - A desktop tool for fast and comprehensive technical audit of the entire website.
Checkbot - Checkbot will boost the SEO, speed and security of your site by checking you're following 50+ web best practices. Browser extension with free and paid plans.
Screaming Frog SEO Spider - The Screaming Frog SEO Spider is a small desktop program (PC or Mac) which crawls websites’ links...
LinkChecker - LinkChecker is a free, GPL licensed website validator.
Pulno - SEO Audit and Website Analysis. Pull up your SEO.
Seodity - The complete SEO toolkit for improving your projects.