SEMrush is a powerful and versatile competitive intelligence suite for online marketing, from SEO and PPC to social media and video advertising research.
Search for any competitor. Download their keywords. It’s that simple. Learn competitors’ PPC & SEO tricks and avoid their mistakes.
Serpstat seems to bring through accurate results and seems to dig a bit deeper than most of the other tools.
KWFinder is a keyword research and analysis tool bringing hundreds of long tail keywords with low SEO difficulty.
Google Keyword Planner
Google AdWords Keyword Planner is a keyword research tool that allows you to find the right keywords to target for display ads, search ads, video ads, and app.
Wordtracker to reveal 1000s of profitable longtail keywords with up to 10000 results per search.