Pulno - SEO Audit and Website Analysis. Pull up your SEO.
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.
Fast Link Checker - An advanced tool to find broken links on web sites.
SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
LinkChecker - LinkChecker is a free, GPL licensed website validator.
Sitechecker - All-in-one SEO platform including rank tracker, website SEO audit tool and website changes monitoring. Detailed reports by 100+ parameters with how-to-fix guides.