AdWords Keyword Generator - Instantly generate thousands of targeted longtail keywords
Ubersuggest - Want more traffic? Ubersuggest shows you how to win the game of SEO. Just type in a domain or a keyword to get started.
Keyword Explorer by Moz - Find the best keywords to improve your website's SEO traffic
Keyword Surfer - Get search volumes & keyword data directly in Google.
Wonpy - The SEO keyword tool for smart Google Ads advertisers
Content Marketing Stack - A curated directory of content marketing resources