Serpstat’s Free Keyword Suggestions Tool: A free keyword suggestion tool with a cool “Only Questions” feature
Serpstat’s Free Keyword Suggestions Tool is the second by the number of suggestions it offers among similar free tools (after KeywordShitter and Keywordini). Unlike Keywordini and SEO Book Keyword Tools, it doesn’t provide CPC and search volume, but gives out a massive keyword list that you can upload into the Google Keyword Planner to check metrics.
SerpStat free tool is excellent for keyword brainstorming. Additionally, it has a really cool and handy “Only questions” filter, that allows you to see questions that people ask around your keyword.
SerpStat also has a freemium keyword research and ranking tool: