About Cosmonic
WebAssembly sandboxes for agent code, MCP servers and tools, with no access until you grant it: the free Cosmonic Desktop app (public beta) and Cosmonic Control for Kubernetes. Open source core: CNCF wasmCloud.
Code Sandboxes
Alternatives to Cosmonic
9 code sandboxes tools you can use instead of Cosmonic, 2 of them open source. Summaries come from each vendor's own site. Links checked Oct 20, 2026.
At a glance
Cosmonic alternatives compared
| Tool | What it does | Open source | Head to head |
|---|---|---|---|
| Agent 37 | Cloud sandboxes for running AI agents, positioned as lower-cost agent infrastructure. | No | Cosmonic vs Agent 37 |
| AIO Sandbox | All-in-one agent sandbox with browser, shell, file access, VSCode Server, and MCP in one container. | Yes | Cosmonic vs AIO Sandbox |
| Cloudflare Sandbox SDK | Run untrusted or generated code in Linux VMs or isolated Workers on Cloudflare. | No | Cosmonic vs Cloudflare Sandbox SDK |
| Daytona | Secure sandboxes for running AI-generated code. Its public GitHub repo is archived: core development moved to a private codebase in June 2026. | No | Cosmonic vs Daytona |
| E2B | Isolated cloud machines for agents to run code, browse, and use tools. | Yes | Cosmonic vs E2B |
| Modal | Serverless cloud for running, training, and serving AI workloads, including sandboxes. | No | Cosmonic vs Modal |
| Runloop | Code sandboxes (Devboxes) for AI coding agents, plus evaluations. | No | Cosmonic vs Runloop |
| Vercel Sandbox | Isolated Linux microVMs on Vercel for untrusted or agent-generated code. | No | Not compared yet |
| VoidRun | Isolated microVM sandboxes where AI agents and developers run untrusted code, via REST API, TypeScript and Python SDKs, and an MCP server (beta). | No | Not compared yet |
Code Sandboxes
All 9 alternatives
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Agent 37
agent37.comCloud sandboxes for running AI agents, positioned as lower-cost agent infrastructure.
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AIO Sandbox
sandbox.agent-infra.comAll-in-one agent sandbox with browser, shell, file access, VSCode Server, and MCP in one container.
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Cloudflare Sandbox SDK
developers.cloudflare.comRun untrusted or generated code in Linux VMs or isolated Workers on Cloudflare.
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Daytona
daytona.ioSecure sandboxes for running AI-generated code. Its public GitHub repo is archived: core development moved to a private codebase in June 2026.
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E2B
e2b.devIsolated cloud machines for agents to run code, browse, and use tools.
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Modal
modal.comServerless cloud for running, training, and serving AI workloads, including sandboxes.
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Runloop
runloop.aiCode sandboxes (Devboxes) for AI coding agents, plus evaluations.
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Vercel Sandbox
vercel.comIsolated Linux microVMs on Vercel for untrusted or agent-generated code.
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VoidRun
void-run.comIsolated microVM sandboxes where AI agents and developers run untrusted code, via REST API, TypeScript and Python SDKs, and an MCP server (beta).
FAQ
Questions
What are the alternatives to Cosmonic?
Agent Stack Directory lists 9 other code sandboxes tools: Agent 37, AIO Sandbox, Cloudflare Sandbox SDK, Daytona, E2B, Modal, Runloop, Vercel Sandbox, VoidRun.
Is there an open-source alternative to Cosmonic?
Yes. Among the alternatives we list, these are marked open source: AIO Sandbox, E2B.
What does Cosmonic do?
WebAssembly sandboxes for agent code, MCP servers and tools, with no access until you grant it: the free Cosmonic Desktop app (public beta) and Cosmonic Control for Kubernetes. Open source core: CNCF wasmCloud. (Summary based on cosmonic.com, link checked 2026-10-20.)