SERPStream is a 100% free SEO tool. Members can keep track of their site's Search Engine Results Page position with updates as frequent as a dozen times a day. SERPStream have a great newsletter, sends email alerts, and have a state of the art keyword rank tracking dashboard.
SerpWatch - Track your rankings with a fast and 100% accurate rank checker. Manage multiple locations and projects with full app integration. Try it for free for 15 days.
Link Assistant - Get all SEO tools in one pack - download free edition of SEO PowerSuite and get top 10 rankings for your site on Google and other search engines!
HubSpot - HubSpot is an inbound marketing and sales platform that helps companies attract visitors, convert leads, and close customers.
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.
SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
SimilarWeb - SimilarWeb.com is a website analysis tool that gives you analytics information for any website.