Really Good UX - A library of screenshots for UX inspiration
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.
UX Archive Animated - iOS apps animated user flows
Fast Link Checker - An advanced tool to find broken links on web sites.
Page Flows - User flow design inspiration for mobile & desktop
Pulno - SEO Audit and Website Analysis. Pull up your SEO.