BuzzSumo is a social media analytics and curation tool for content marketers. It searches the web for content based on search queries and reports back to the enquirer on its success, based upon its social likes & shares.
iSpionage is an advanced keyword research tool allowing for numerous keyword management and competitive analysis features many people (especially PPC marketers) will find useful.
Clicky Web Analytics is simply the best way to monitor, analyze, and react to your blog or web site’s traffic in real time.
Serpstat is an all-in-one SEO platform, which consists of five different modules and is used for Keyword Research, Competitor Analysis, Site Audit, Backlink Analysis and Rank Tracking.
Yoast is currently considered the most comprehensive search engine optimization software available for WordPress users.
SpyFu is an industry-leading competitive keyword research tool.