Fly.io Sprites
Last verified 2026-08-09
Sprites are Fly.io's purpose-built agent sandboxes, distinct from Fly Machines: each is a hardware-isolated Firecracker microVM with a persistent, thin-provisioned ext4 filesystem that syncs to object storage, so an environment comes back exactly as left even months later. Checkpoints are copy-on-write and take about 300ms. The VM is disposable and pauses when idle, and per-Sprite egress is controlled by a domain allow/deny policy. Launched in 2026 with JS, Python, Go and Elixir SDKs.
Key specs
| Isolation | Firecracker microVM |
| Price / vCPU-hr | $0.07 |
| Pricing model | Per-hour usage (CPU + memory + storage) |
| GPU | No |
| Session limit | Persistent (pauses when idle) |
| Persistence | Persistent ext4 (NVMe + object storage), roughly 300ms checkpoint/restore |
| Languages | any (real Linux VM) |
| MCP support | n/a |
| Deployment | Managed cloud (Fly.io) |
| CPU | $0.07/CPU-hr |
| Memory | $0.04375/GB-hr |
| Checkpoints | roughly 300ms |
Strengths
- Persistent filesystem that survives idle
- Fast (roughly 300ms) copy-on-write checkpoints
- Firecracker microVM isolation
- Zero cost when idle; per-Sprite egress policy
Trade-offs
- No GPU
- Newer product (launched 2026)
- Requires a Fly.io account
Best for: Agents and dev workflows that need a persistent, resumable Linux environment with fast checkpoints.
How Fly.io Sprites work
Sprites are Fly.io's agent-focused sandboxes, separate from Fly Machines. Each Sprite is a hardware-isolated Firecracker microVM with a persistent, thin-provisioned ext4 filesystem that continuously syncs to durable object storage, so files, installs and databases sit on the same paths every run and a Sprite untouched for months boots back exactly as left. The VM itself is disposable: it spins up when there is work and pauses when idle, so you pay for real usage. Checkpoints are copy-on-write and take about 300ms, capturing the whole writable filesystem for quick rollback.
Setup, limits & watch-outs
Pricing is hourly on actual usage: $0.07 per CPU-hour, $0.04375 per GB-hour of memory, and tiered storage that bills for bytes actually written (hot at $0.000683/GB-hour, cold far less). A Sprite can burst to 8 vCPUs, grows memory under load, and each has its own URL that wakes it on an incoming request. Egress is governed by a per-Sprite domain allow/deny policy with sensible defaults for GitHub, npm, PyPI and common AI APIs. It runs a base Linux image and uses your Fly.io account; there is no GPU, and the product is new (launched 2026), so its operational track record is still building.
Head-to-head
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Sources: Fly.io Sprites ↗ · Sprites (sprites.dev) ↗
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