AI code-execution sandbox
Fly.io Machines
Fly.io Machines are fast-booting microVMs with a persistent ext4 filesystem, ~300ms checkpoints, zero idle cost and a native MCP endpoint.
Last verified 2026-07-26
Fly.io Machines (marketed as "Sprites" for agent use) are hardware-virtualized microVMs with persistent ext4 filesystems, ~300ms checkpoints, zero idle cost when stopped, and a native MCP endpoint — a flexible, low-level primitive for agent workloads.
Key specs
| Isolation | microVM |
| Cold start | 300ms |
| Price / vCPU-hr | $0.07 |
| Pricing model | Usage + concurrency plans |
| GPU | GPUs available |
| Session limit | Persistent |
| Persistence | Persistent ext4 filesystem, checkpoints |
| Languages | any |
| MCP support | Yes |
| Integrations | MCP, REST/API |
| Deployment | Managed cloud (global regions) |
| Free tier | Pay-as-you-go |
| CPU rate | $0.07/CPU-hr |
| Checkpoints | ~300ms |
Strengths
- Zero idle cost
- Native MCP endpoint
- Persistent filesystem
- Global regions
Trade-offs
- Lower-level (more assembly required)
- Less agent-specific SDK sugar
Best for: Teams wanting a low-level, MCP-native VM primitive with zero idle cost.
Alternatives to Fly.io Machines
E2B — AI code-execution sandboxDaytona — AI code-execution sandboxModal — AI code-execution sandboxVercel Sandbox — AI code-execution sandbox
Sources: Fly.io Machines docs ↗
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