PySOT is a SenseTime research platform for single object visual tracking. It provides implementations of state-of-the-art Siamese-network-based tracking algorithms including SiamRPN, SiamRPN++, DaSiamRPN, SiamMask, and SiamFC. The project is written in Python using the PyTorch framework and includes various backbone architectures (ResNet, MobileNetV2, AlexNet). It also contains an evaluation toolkit for benchmarking trackers.