Celesto (SmolVM) alternatives
The 6 alternatives below are grouped by kind of sandbox, and each says what it does differently from Celesto (SmolVM). Start from whatever made you look: missing GPUs, session limits, self-hosting, pricing or isolation.
Why teams look beyond Celesto (SmolVM)
A young, alpha-labelled but feature-rich open-source microVM runtime that is easy to try locally on macOS or Linux and has a per-hour cloud behind it.
- Alpha-labelled release line; the project name changed from SmolVM to Celesto and documentation is split across the old and new names
- Network policy controls are Linux/Firecracker only; the macOS QEMU backend is documented as 3-4x slower for lifecycle operations
- No compliance, region or session-limit documentation
Celesto (SmolVM) alternatives, by kind
Hosted sandbox platforms
SDK-driven sandboxes you create, run code in and destroy through an API.
E2B
Open-source cloud sandboxes for AI agents, each a Firecracker microVM, with pause/resume, snapshots and forking.
- Firecracker microVM
- Open source
- Self-hostable
- BYOC
- Pause/resume
How it differs: Code interpreters and short-to-medium-lived agent tasks that need microVM isolation, with an open-source self-host path. The safe default for most agent builders: mature, open source, microVM-isolated and widely supported.
Open-source runtimes to self-host
Open-source sandbox runtimes you run on your own servers or Kubernetes.
Arrakis
Self-hosted microVM sandbox for agent code execution and computer use, with snapshot-and-restore and a VNC-accessible GUI in every VM.
- Cloud Hypervisor microVM
- Open source
- Self-hostable
- Snapshots
How it differs: Self-hosting a GUI-capable microVM sandbox with snapshot/restore for computer-use and code-execution agents. A single-maintainer, AGPL microVM sandbox that stands out for bundling a GUI and snapshot/restore for self-hosters on Linux.
BoxLite
Embeddable, daemonless microVM library that runs OCI images in hardware-isolated boxes on a laptop or server, with an optional managed cloud.
- microVM + jailer
- Open source
- Self-hostable
How it differs: Embedding a microVM sandbox directly in your own process on a laptop or server without running a daemon. A practical choice when you want microVM isolation embedded in your own process rather than behind a service.
Microsandbox
Open-source, local-first microVM runtime that gives each sandbox its own Linux kernel, with an optional managed cloud.
- MicroVM (libkrun)
- Open source
- Self-hostable
- BYOC
- Snapshots
How it differs: Self-hosted microVM isolation on developer machines or your own servers. The most approachable way to get microVM-grade isolation locally or self-hosted.
Isolation primitives and runtimes
The hypervisors, user-space kernels, OS sandboxes and WebAssembly runtimes that sandbox platforms build on.
Firecracker
The KVM-based microVM monitor from AWS that underpins Lambda and Fargate, and the sandboxes of E2B, Vercel, Fly.io, Koyeb and Northflank.
- KVM microVM
- Open source
- Self-hostable
- Pause/resume
How it differs: Building your own microVM sandbox fleet on Linux hosts with KVM. The reference microVM primitive for sandbox platforms; choose it when you are building a platform rather than consuming one.
Local sandboxes for coding agents
Isolation for agents like Claude Code, Codex or Gemini CLI on your own laptop.
agents-sandbox
GPL-3.0 launcher that gives each project and coding agent its own microsandbox microVM on Linux/KVM or Apple Silicon macOS, with secrets kept on the host.
- microsandbox microVM
- Open source
How it differs: Developers who want each coding agent confined to a per-project microVM on their own Linux or Apple Silicon machine. A focused per-project microVM launcher for opencode users; support for other agents is still experimental.
Celesto (SmolVM) vs alternatives
| Sandbox | Isolation | Open source | Self-host / BYOC | Cold start (vendor) | Max session | Snapshots / pause | GPU | SDKs |
|---|---|---|---|---|---|---|---|---|
| Celesto (SmolVM) | Firecracker / QEMU microVM | Yes | Yes / No | ~500 ms (claim) | Not documented | Yes / Yes | Not documented | Python, JavaScript/TypeScript, CLI, MCP server |
| agents-sandbox | microsandbox microVM | Yes | No / No | Not documented | Not documented | Not documented / Not documented | Not documented | CLI |
| Arrakis | Cloud Hypervisor microVM | Yes | Yes / No | Not documented | Not documented | Yes / Not documented | Not documented | Python, REST API, CLI, MCP server |
| BoxLite | microVM + jailer | Yes | Yes / No | ~1 s (claim) | Not documented | Not documented / Not documented | Not documented | Python, JavaScript/TypeScript, Go, Rust, C, CLI, REST API |
| E2B | Firecracker microVM | Yes | Yes / Yes | Not documented | 1 h / 24 h (Pro) | Yes / Yes | No | Python, JavaScript/TypeScript |
| Firecracker | KVM microVM | Yes | Yes / No | <125 ms (spec) | Not documented | Yes / Yes | No | 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 |
Frequently asked questions
What are the main alternatives to Celesto (SmolVM)?
Is there an open-source alternative to Celesto (SmolVM)?
Cite this page
Agent Sandboxes. (2026). Celesto (SmolVM) alternatives. agentsandboxes.org. Last reviewed November 9, 2026. https://agentsandboxes.org/alternatives/smolvm/
Found an error or a missing sandbox? Submit a correction — every entry links to the sources it relies on.