K-Scale Labs builds open-source humanoid robot platforms including the full-size K-Bot and the 4-foot Stompy robot. K-Bot provides mechanical and electrical hardware designs under CERN-OHL-S license and software under GPL v3, incorporating modules for inference, operating system, and simulation. Stompy employs quasi-direct drive actuators with 6:1 to 8:1 reduction ratios, low-inertia back-drivable joints delivering 3-12 Nm torque, and a hot-swappable 48V 15Ah battery for over one hour of runtime; its parts fit on a 256x256 mm 3D printer bed using carbon fiber PAHT plastic, with total bill of materials under $10,000. The company supplies software such as ksim for reinforcement learning using MuJoCo and JAX, and kinfer for model export and inference in Rust. These robots serve developers building embodied AI applications, with K-Bot sold for $8,999. Founded in 2024 by Benjamin Bolte (CEO, ex-Tesla Optimus perception CUDA kernel developer and Meta AI robotics researcher with highly cited papers) alongside co-founder Paweł Budzianowski (ML lead, Cambridge PhD in conversational AI). The startup participated in Y Combinator's Winter 2024 batch and was headquartered in Palo Alto, California.