SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
Google Trends - Explore Google trending search topics with Google Trends.
Pro Rank Tracker - Rank tracking & reporting software solution
KeywordTool.io - KeywordTool.io is the best FREE alternative to Google Keyword Planner and Ubersuggest. It uses Google's autocomplete feature to get over 750+ long-tail keywords for any given query.
SEOmator - SEO website analysis & audit tool
Keywords Everywhere - Free browser add-on for keyword volume, CPC & competition