Bit.ly is a very useful tool for social media analytics. As a free option, this link shortener can provide useful data on who is opening your posted link, where they are opening, at what time, and how they received that link. If someone retweets a link you tweeted bit.ly will track that link and provide you with data to how it is being used.
This tool is great for evaluating what platform of social media is engaging the largest number of consumers. In the rapidly evolving world of social media analytics Bit.ly has been a mainstay as the premier link shortener. They continue to innovate this platform to provide more and more useful data.