Google Open Source - All of Googles open source projects under a single umbrella
Ubersuggest - Want more traffic? Ubersuggest shows you how to win the game of SEO. Just type in a domain or a keyword to get started.
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
Keyword Surfer - Get search volumes & keyword data directly in Google.
Open Source @IFTTT - A collection of IFTTT OSS projects.
Keyword Tool & Content Assistant - Content optimization tool to boost your rankings