Here is the mission statement from Twitter.
Our company culture directly aligns with its purpose as a platform — a place for discovery, self-expression and human connection. At Twitter, we have created an environment where people are actually encouraged to bring their authentic selves and their passions to work.
Once here, our employees have a myriad of opportunities to grow new skills and deepen those they already possess. Above all, we have created a place where employees come together as empowered individuals for the strength of the collective.
As a product, Twitter brings you closer to others. As an employer, Twitter does the same. We often hear employees say, “I joined Twitter, and I joined a family.”