CubeSandbox
Tencent Cloud's open-source, E2B-compatible sandbox platform that runs each sandbox in a RustVMM/KVM microVM with copy-on-write snapshots. A fast-moving, well-specified microVM platform for teams that want E2B semantics on their own Linux hosts.
Overview
CubeSandbox is a sandbox platform open-sourced by Tencent Cloud in April 2026. Each sandbox is a microVM with its own kernel managed by a Rust hypervisor (CubeHypervisor, built on RustVMM and KVM, with Cloud Hypervisor and Kata Containers acknowledged upstream), and a REST gateway (CubeAPI) and reverse proxy (CubeProxy) implement the E2B API so that the E2B Python, JavaScript or Go SDKs work by changing E2B_API_URL. A single-node install is a one-line script on x86_64 Linux (PVM mode needs no bare metal or nested virtualisation; ARM64 needs native KVM), and CubeMaster orchestrates multi-node clusters with Kubernetes and Terraform deployment options and a web console with a template store.
The README claims sub-60 ms creation via snapshot clones that skip kernel boot, under 5 MB memory overhead and thousands of sandboxes per node. The CubeCoW engine provides copy-on-write snapshots, rollback and forking, and v0.7.0 (August 2026) added cross-node pause/resume backed by S3. Networking uses an eBPF virtual switch and an OpenResty egress gateway that filters domains and injects credentials so secrets never enter the sandbox. Minimum host is 4 cores, 8 GB RAM and 50 GB of XFS disk; GPU sandboxes and automatic crash recovery are roadmap items. There is no hosted service: cubesandbox.com documents self-build and cluster deployment only.
Notable
- Initial open-source release v0.1.0 on 20 April 2026; v0.7.0 on 28 August 2026 added cross-node pause/resume with an S3 backend
- Apache-2.0, listed in the CNCF Landscape, roughly 13k GitHub stars
- README claims 60 ms cold start at single concurrency and P99 137 ms at 50 concurrent creations on bare metal
CubeSandbox specifications
| Attribute | Details |
|---|---|
| Isolation | Dedicated microVM per sandbox with its own guest kernel, built on RustVMM and KVM (CubeHypervisor), with eBPF-based network isolation and egress filtering |
| Deployment | Open-source project · Self-hostable |
| Open source | Yes (Apache-2.0) |
| SDKs and interfaces | Python, JavaScript/TypeScript, Go, REST API, CLI |
| Cold start (vendor claim) | README: sandboxes created in under 60 ms at single concurrency, average 67 ms / P95 90 ms / P99 137 ms at 50 concurrent creations, measured on bare metal; memory overhead claimed under 5 MB per sandbox |
| Max session length | Not documented |
| Persistence | CubeCoW copy-on-write snapshot engine with cloning, rollback and forking from saved state; AutoPause/AutoResume for idle sandboxes; cross-node pause/resume with an S3 backend (v0.7.0); creating sandboxes from snapshots is a preview; pluggable volumes (S3, host mounts, shared block) |
| GPU | No — GPU sandboxes are on the roadmap, not available |
| Networking | eBPF virtual switch (CubeVS) for inter-sandbox isolation and policy; CubeEgress gateway for L7 domain filtering, credential injection and auditing; per-sandbox traffic tokens |
| Pricing | Free to self-host (Apache-2.0); no hosted offering is described |
| Free tier | Free to self-host |
| Compliance | Not documented |
| Regions | Self-hosted; Terraform one-click deployment on Tencent Cloud |
Facts from CubeSandbox’s public documentation, verified November 9, 2026. Performance numbers are vendor claims.
Strengths and trade-offs
Strengths
- You want E2B-compatible SDKs against infrastructure you run yourself
- You need microVM isolation with snapshot forking and rollback for agent branching or evaluation
- You run on Tencent Cloud or want a Terraform path onto it
- You need credential injection at the egress gateway so keys never reach the sandbox
Trade-offs
- Self-host only; no managed service, so you operate the hypervisor fleet
- Linux hosts only, with x86_64 PVM for the easy path and OpenCloudOS or TencentOS recommended
- No GPU sandboxes yet; snapshot-based creation and Kubernetes deployment are labelled preview in places
- Young project (first release April 2026) with several E2B API gaps listed on the roadmap
Good fit for: Self-hosted, E2B-compatible microVM sandboxes at high density on your own Linux hosts.
Use cases CubeSandbox fits
- Open source & self-hosted: Tencent Cloud’s Apache-2.0, E2B-compatible microVM sandbox built on RustVMM and KVM for high density on your own hosts.
How CubeSandbox compares
| Sandbox | Isolation | Open source | Self-host / BYOC | Cold start (vendor) | Max session | Snapshots / pause | GPU | SDKs |
|---|---|---|---|---|---|---|---|---|
| CubeSandbox | RustVMM/KVM microVM | Yes | Yes / No | <60 ms (claimed) | Not documented | Yes / Yes | No | Python, JavaScript/TypeScript, Go, REST API, CLI |
| E2B | Firecracker microVM | Yes | Yes / Yes | Not documented | 1 h / 24 h (Pro) | Yes / Yes | No | Python, JavaScript/TypeScript |
| OpenSandbox | Containers or Firecracker | Yes | Yes / No | 64 ms P50 (claimed) | Not documented | Not documented / Yes | Not documented | Python, JavaScript/TypeScript, Java, Kotlin, Go, C#, CLI, MCP server, REST API |
| SPACE | Firecracker microVM | Yes | Yes / No | Not documented | 6 h idle suspend | Yes / Yes | Not documented | Python, REST API, CLI |
| Microsandbox | MicroVM (libkrun) | Yes | Yes / Yes | <100 ms | Not documented | Yes / Not documented | No | TypeScript, Python, Rust, Go, Ruby, CLI, MCP server |
| Firecracker | KVM microVM | Yes | Yes / No | <125 ms (spec) | Not documented | Yes / Yes | No | REST API, CLI |
| Kata Containers | VM per pod | Yes | Yes / No | Not documented | Not documented | Not documented / Not documented | Yes | CLI |
Frequently asked questions
What is CubeSandbox?
How does CubeSandbox isolate code?
Is CubeSandbox open source?
How much does CubeSandbox cost?
What are the alternatives to CubeSandbox?
Sources
Cite this page
Agent Sandboxes. (2026). CubeSandbox. agentsandboxes.org. Last reviewed November 9, 2026. https://agentsandboxes.org/sandboxes/cube-sandbox/
Found an error or a missing sandbox? Submit a correction — every entry links to the sources it relies on.