# CubeSandbox

> CubeSandbox, open-sourced by Tencent Cloud on 21 April 2026 under Apache-2.0, runs each agent in a KVM-isolated microVM built on RustVMM: it reports a best-case cold start under 60ms (about 67ms average) and under 5MB memory overhead per sandbox, and is API-compatible with the E2B SDK.

Tencent Cloud's open-source microVM agent sandbox, E2B-SDK compatible.

- **Category:** Execution Sandbox
- **License:** Apache-2.0
- **Language:** Rust
- **Self-hosted:** Yes
- **GitHub stars:** 12798 (2026-10-04)
- **Repository:** https://github.com/TencentCloud/CubeSandbox
- **Last verified:** 2026-10-04

> Caveat: The <60ms figure is a best case at low concurrency; P95 is ~90ms and P99 ~137ms under 50 concurrent creates on bare metal per the project.

Source: https://agent.c8.fit/tools/cubesandbox/