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.
Hunter - Find all the email addresses related to a domain
Google Trends - Explore Google trending search topics with Google Trends.
Apollo.io - Apollo’s predictive prospecting, sales engagement, and actionable analytics help the teams to reach its full revenue potential.
Keywords Everywhere - Free browser add-on for keyword volume, CPC & competition
Icypeas - This email finder has the capacity to bypass catch-alls