Modal Scales 1 Million Sandboxes Without Kubernetes

Modal engineers Colin Weld and Connor Adams rebuilt their sandbox infrastructure to bypass Kubernetes, which struggles with centralized coordination at scale. Their parallel scheduling servers and worker-owned state created 1 million sandboxes in under a minute, with median startup-to-code time under 0.5 seconds. AWS principal AI engineer Alex Jones calls it the first credible signal Kubernetes isn't adapting fast enough for GenAI infrastructure.