Keyword Surfer - Get search volumes & keyword data directly in Google.
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.
PPC Gear - Instantly find where you lose money in Google Ads
Google Trends - Explore Google trending search topics with Google Trends.
AdWords Keyword Generator - Instantly generate thousands of targeted longtail keywords
Keywords Everywhere - Free browser add-on for keyword volume, CPC & competition