CubeSandbox
harnessAssess
CubeSandbox (Tencent Cloud, Apache 2.0) is a self-hostable sandbox infrastructure for securely running LLM-generated code - the isolation layer behind the Code Execution pattern. It uses microVMs (rust-vmm + KVM, own guest kernel per sandbox) with network isolation, and its API is E2B-SDK-compatible.
- Reported <60ms cold start and thousands of sandboxes per node.
- Very young (public since ~July 2026, still 0.x with a high release churn) - production-readiness claims warrant caution.
- Self-hosted on own KVM hardware it is data-friendly; Needs Linux/KVM bare-metal or nested virtualization.
CubeSandbox is worth watching as a self-hosted alternative.