Linkody - Save time and money by managing your SEO linkbuilding with Linkody.
Watchtower - "Watchtower monitors your competition's websites and alerts you to important changes instantly."
Backlinks by Neil Patel - A backlinks research tool for competitive intelligence
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
SE Ranking - All-in-One cloud-based SEO software for agencies, marketing teams and webmasters
Material Design for Bootstrap 4 - Powerful and free UI KIT for the newest Bootstrap 4 and Material Design