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Sandboxer vs Sail Sailboxes

Sailboxes from Sail Research are persistent Linux VMs for long-horizon agents, with pause, resume and fork of all state and billing on active usage only. It differs from Sandboxer mainly in active-usage billing and its inference integration. Pick Sailboxes for active-only metering and its Pro tier of up to 5,000 concurrent Sailboxes; pick Sandboxer for preinstalled coding agents, nested KVM and plan-based pricing.

Checked against Sail Sailboxes' public docs on October 24, 2026. Sources are linked in the table and listed below.

At a glance

Sandboxer and Sail Sailboxes compared
CapabilitySandboxerSail Sailboxes
IsolationmicroVM
Cloud Hypervisor, its own kernel
kernel-isolated Linux VM
Hypervisor not named.
Full Linux with root
Ubuntu 24.04, sudo, systemd
Root access included.
Docker inside
Preinstalled
Docker-in-Docker listed as supported.
Nested virtualization (/dev/kvm)
Pause and resume with memory
Running processes come back
In-flight work survives pause; open connections up to 10 minutes.
Fork a sandbox
Copy-on-write disk copy that boots fresh
Pause, resume and fork of all sandbox state (state fork, not clearly process-preserving).
HTTPS URL per port
Private with a token, or public
Longest sessionNo limit on paid plans
Auto-stop is up to 30 days or off
no limit
No fixed limit.
BillingPer second, flat rate per size
Stopped sandboxes are free
per second, billed per minute; active vCPU, RAM held, disk used
$0.015/vCPU-h, $0.008/GB-h; sleeping or paused not billed.
GPUs
Self-host or open source
RegionsUS East (Virginia) and EU Central (Finland)

= not documented publicly.

Price for one 4 vCPU, 8 GB machine

Sandboxer
$0.036/hour
Flat per-second rate for the default size
Sail Sailboxes
$0.12/hour
4 vCPU × $0.015/h + 8 GB × $0.008/h (assumes fully active CPU; excludes disk and creation fee)

List prices from each provider's pricing page, before free credits, plans and storage. This compares price only.

Where Sail Sailboxes is strong

  • Active-usage billing: sleeping and paused time is not billed.
  • Pause, resume and fork of full sandbox state.
  • No fixed runtime limit.
  • Root, Docker-in-Docker and persistent NVMe disks.

Where Sandboxer differs

  • Sailboxes bill CPU only when used, while Sandboxer bills fixed hourly sizes.
  • Sailboxes can sleep while waiting on Sail inference calls, an integration with Sail's inference platform that Sandboxer does not have.
  • Sail docs fetched do not state nested virtualization, public per-port URLs, GPUs or regions.

Pick Sail Sailboxes if

  • You want billing on active CPU only for bursty agents.
  • You need up to 5,000 concurrent sandboxes on Pro.
  • You already use Sail's inference.

Pick Sandboxer if

  • You need a full Ubuntu 24.04 VM with root, systemd, Docker and nested KVM rather than a bare sandbox runtime.
  • You want coding agents preinstalled in every sandbox and driven through a prompt API with streamed events.
  • You want a fixed per-size hourly price (default 4 vCPU/8 GB at $0.036/h) with plan dollars returned as machine time.

Sources

Products change. If something here is out of date, email hello@sandboxer.com and we'll fix it. Sail Sailboxes is a trademark of its owner. Sandboxer is an independent product and is not affiliated with Sail Sailboxes.

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