CreateOS Sandbox vs Fly.Io Machines
Fly.io Machines suit developers who want programmable VMs in many regions and will build their own exec and lifecycle layer. CreateOS Sandbox suits teams who want that layer already there: exec, files, fork from paused and outbound rules, in eu or us.
Pricing at a Glance
CreateOS rates verified 17 October 2026. Fly.io Machines pricing as published on 17 October 2026. Rates billed per GB rather than per GiB, or as bundled sizes, are quoted as published rather than converted.
CreateOS Sandbox
- Compute
- $0.0362 /vCPU-hr
- Memory
- $0.0116 /GiB-hr
Fly.io Machines
Fly.io Machines bill per second, quoted monthly in iad from $2.19 per month (shared-cpu-1x, 256MB) and $33.00 per month (performance-1x, 2GB), plus egress from $0.02 per GB in North America and Europe, as of 17 October 2026.
Where CreateOS Sandbox Fits Better
What CreateOS Sandbox brings to this matchup, with a plain note on where Fly.io Machines has the edge.
Exec, file transfer, managed processes and shell built into the API; with Machines you build your own exec and file layer.
Fork a paused sandbox into many copies; fork is not published for Machines.
Disk survives pause and resume, where a Machine's root filesystem is blank on every start unless you attach a volume.
No per-GB egress fee within a 50 GiB default budget per sandbox; Fly charges $0.02 to $0.12 per GB by region.
Where Fly.io Machines is strong
Fly gives you real Firecracker VMs behind a simple REST API that start in well under a second (vendor-stated), in 17 regions, with memory-snapshot suspend, a mature global proxy and SOC 2 Type 2 (vendor-stated). L40S GPU Machines remain available.
Which to Pick
Pick CreateOS Sandbox if
- You want exec, files and shell without writing an agent in the guest.
- You need to fork environments or restrict their outbound traffic.
- You want outbound data with no per-GB fee inside a 50 GiB budget per sandbox.
Pick Fly.io Machines if
- You want VMs placed close to users in many regions.
- You are happy to build your own orchestration on a VM API.
- You also run production apps behind Fly's proxy.
Head-to-Head Comparison
Every dimension side by side, checked on 17 October 2026 against each vendor's own docs and pricing pages. "Not published" means we could not find it on the vendor's pages, not that the feature is missing.
| Dimension | CreateOS Sandbox | Fly.io Machines |
|---|---|---|
| Built for | Sandboxes created by API for agent and untrusted code | Apps and per-user or per-task VMs close to users |
| Isolation | Firecracker micro-VM with its own guest kernel | Firecracker microVM |
| Ephemeral per-run environments | Yes: create a sandbox per run by API and destroy it after | Yes: create and destroy Machines by REST API; root filesystem is blank on every start |
| Pause and resume | Yes: pause saves disk, memory and CPU state; vCPU stops billing, memory and storage still bill | Suspend captures memory and CPU registers in a Firecracker snapshot; not recommended above 2 GB RAM |
| Outbound network | Open with no rules; deny-by-default once any host, IP, CIDR or wildcard rule exists, enforced on the host outside the VM | Not published for Machines; egress $0.02 to $0.12 per GB by region |
| Billing | Per second: $0.03616363 per vCPU-hour, $0.01159025 per GiB-hour, storage $0.0001584 per GB-hour | Per second, quoted monthly; shared-cpu-1x 1GB $6.70/month in iad; regional multipliers |
| Run untrusted code | Yes: each sandbox is its own micro-VM, with host-enforced outbound rules and inbound closed by default | Possible, but exec, file and lifecycle layer is yours to build; Fly sells Sprites for sandboxing |
Common Questions
Can Fly.io Machines suspend with memory like CreateOS pause?
Yes. Fly suspend saves memory and CPU registers in a Firecracker snapshot, but Fly does not recommend it above 2 GB of RAM. CreateOS pause also saves disk, memory and CPU state, and a paused sandbox can be forked into new copies.
Do I need to build my own exec layer on Fly.io Machines?
Yes. Machines run your container image, and running commands or moving files inside them is up to you. CreateOS exposes exec, file transfer, managed processes, shell and port tunnels through its REST API, SDKs and CLI.
How many regions do Fly.io Machines cover compared with CreateOS?
Fly lists 17 regions, from ams and fra to nrt, sin, syd and gru. CreateOS Sandbox runs in two managed regions, eu and us, so Fly wins when code must run near users in Asia, South America or Africa.
What is Fly.io Sprites and how does it relate to Machines?
Sprites is a separate Fly product for persistent sandboxes with checkpoints and an egress policy, sold alongside Machines. This page compares Machines; the Machines docs do not publish fork or an egress policy.
Sources
Checked 17 October 2026.
See CreateOS Sandbox for yourself
Book a demo, or explore the Sandbox and its pricing.