SEO & Keyword Research

Google Keyword Planner: Nothing like searching for keywords using the tool created by big G himself.

Semrush: The very best SEO tool available. Research on your competitors, do keyword research, and much more.

Long Tail Pro: Find Long-tail keywords with this software.

Ubersuggest: Google suggestion on steroids – find lots of keyword suggestions for a given keyword!

WordPress SEO by Yoast: Best SEO plugin for WordPress users.