Verisig is a tool for verifying safety properties of autonomous systems with neural network (NN) controllers.  Verisig  supports sigmoid and tanh-based networks and exploits the fact that the sigmoid (and the tanh) is the solution to a quadratic differential equation, which allows us to transform the neural network into an equivalent hybrid system. By composing the network's hybrid system with the plant's, Verisig transforms the problem into a hybrid system verification problem which can be solved using state-of-the-art reachability tools. Specifically, Verisig uses Flow* to solve the resulting hybrid system reachability problem. Verisig is available at verisig.org, and the code can be found at https://github.com/verisig.