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LinkChecker - LinkChecker is a free, GPL licensed website validator.
Screaming Frog SEO Spider - The Screaming Frog SEO Spider is a small desktop program (PC or Mac) which crawls websites’ links...
DRKSpiderJava - DRKSpider is an open source website crawler (sitemap generator) and link checker. Features:
SiteAnalyzer - SiteAnalyzer it's a desktop Crawler, designed to SEO audit and analyze website content to identify technical and SEO-optimization errors. After scanning your website, SiteAnalyzer will display all the technical and SEO errors and help to fix them!
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.