Cloudflare Sandbox SDK
Last verified 2026-07-26
Cloudflare Sandbox SDK is a hybrid: ~50ms V8 isolates for lightweight work and containers for full environments, with "Code Mode" support. It rides the Workers Paid plan ($5/mo) plus active-CPU billing and is currently in beta with a 30-minute execution cap.
Key specs
| Isolation | V8 isolate + container |
| Cold start | 50ms |
| Price / vCPU-hr | $0.072 |
| Pricing model | Workers Paid + active CPU |
| GPU | No |
| Session limit | 30min execution cap |
| Persistence | Durable Objects state |
| Languages | JavaScript/TypeScript, containerized runtimes |
| MCP support | Yes |
| Integrations | OpenAI Agents SDK, Workers AI |
| Deployment | Managed (Cloudflare edge) |
| Free tier | Workers free tier for isolates |
| Base | Workers Paid $5/mo |
| Active CPU | ~$0.072/vCPU-hr |
Strengths
- ~50ms isolates
- Bundled with Workers ($5/mo)
- Global edge
Trade-offs
- Beta
- 30-min execution cap
- Container cold start slower
Best for: Edge-native apps and teams already on Cloudflare Workers.
How Cloudflare Sandbox SDK works
Cloudflare's Sandbox SDK is a hybrid. Lightweight work runs in V8 isolates, the same technology behind Workers, which start in about 50ms because they share a process instead of booting a machine. Heavier work runs in full containers, which start slower. State persists through Durable Objects, and there is a 'Code Mode' plus MCP support. It runs on Cloudflare's edge, so it sits close to users globally. This fits teams already building on Workers who want code execution in the same runtime rather than a separate service to wire up.
Pricing in practice & watch-outs
The model is the $5 a month Workers Paid plan plus active CPU at roughly $0.072 per vCPU-hour, so if you already run Workers the sandbox rides on a plan you have. The caveats are real. It is in beta, so treat it as not yet settled for production and expect changes. Execution is capped at 30 minutes, which rules out long jobs. And while V8 isolates start in about 50ms, the container path for full environments is noticeably slower to start, so the headline number only applies to the lightweight tier.
Head-to-head
Alternatives to Cloudflare Sandbox SDK
See the full Cloudflare Sandbox SDK alternatives comparison →
Sources: Cloudflare Workers docs ↗
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