SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
Xenu's Link Sleuth - Xenus Link Sleuth checks Web sites for broken links.
Lumar - (Previously DeepCrawl) Hosted SEO spider to analyze and find problems with websites.
Scrutiny - Scrutiny for Mac helps you manage and improve any number of websites. Link check, search, full website spell check, XML sitemap generator, SEO audit
Website Checker Tech - WebsiteChecker.Tech is SaaS tool that detects SEO and availability issues of your website, making it easier for you to fix them.
LinkChecker - LinkChecker is a free, GPL licensed website validator.