Agent sandboxes / Sandbox as a Service alternative

A Sandbox as a Service alternative for a returning agent computer

Sandbox as a Service provides disposable dedicated VMs with simple prepaid, per-second billing. It also supports full-VM disk images, so it is not limited to copying a workspace folder. The important distinction for returning agents is a new VM restored from a short-retention image versus keeping one durable sandbox identity and growing its RootFS online.

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Reviewed 2026-10-18 · Published by the Sandbox0 team

When Sandbox as a Service fits

Sandbox as a Service fits bounded code-execution jobs, disposable testing and agent tools that can finish within the VM lifetime and export or snapshot their results. Its three fixed machine sizes make the wall-clock compute charge straightforward to estimate.

When to consider Sandbox0

Consider Sandbox0 when a user returns repeatedly to installed software, system settings and accumulating data on the same sandbox identity. Growth-enabled RootFS expansion and supported paused file access help that workflow; choose compatible memory pause explicitly if processes must continue.

Capabilities

Sandbox as a Service and Sandbox0: what persists?

Feature comparison with documentation and verification status
Environment and runtime lifetimeSandbox as a ServiceThe absolute maximum is 1,440 minutes, including extensions; this is a 24-hour cap, not an indefinite session.View evidence ↗Sandbox0ttl and hard_ttl default to 0 (disabled). Configure idle pause and deletion policies for the same persistent sandbox identity; an idle running sandbox still accrues compute charges.Read documentation →
Persistent filesSandbox as a ServiceFull disk snapshots retain captured state for seven days; destroying an unsnapshotted VM loses its filesystem.View evidence ↗Sandbox0The writable RootFS survives successful checkpoints, including software, system configuration, dependencies, and user data.Read documentation →
Whole RootFSSandbox as a ServiceA snapshot captures the VM disk including installed packages, and restores it into a new same-size VM.View evidence ↗Sandbox0Persistence extends beyond /workspace to paths such as /usr/local, /etc, and /home. Runtime tmpfs and virtual filesystems are excluded.Read documentation →
Release compute, keep stateSandbox as a ServiceThe documented image-restore workflow boots a new VM; a retained execution pause is not established.View evidence ↗Sandbox0Pause compute between tasks; resume on available capacity. Default resume starts fresh processes from the saved filesystem.Read documentation →
Memory and process stateSandbox as a ServiceRestore explicitly starts new processes rather than resuming the source execution state.View evidence ↗Sandbox0Experimental memory checkpoints can preserve compatible process state. Use memory: true on both pause and resume on a compatible deployment. A filesystem checkpoint alone does not preserve running processes.Read documentation →

Online RootFS growth

On growth-enabled images, Sandbox0 automatically expands the writable RootFS as free space runs low, within a configured sparse logical ceiling up to 64 TiB. Agent processes keep running. Growth is enabled in the qualified Cloud region; confirm activation for other regions. Existing images and snapshots retain their captured storage geometry. The ceiling is logical capacity, not preallocated host disk.

VM CPU, RAM and disk are fixed for the entire life of a Sandbox as a Service VM; resizing is not supported, and a snapshot must restore to the captured size. This differs from growth-enabled Sandbox0 templates expanding XFS online as free space runs low.

Files while compute is paused

Sandbox0's Files API reads persistent files without resuming compute. Filesystem-only pauses also permit edits; retained-memory pauses are read-only and reject mutations with 409. SSH, SFTP, file watching, and runtime-only mounts require running compute.

See paused file operations →

The deadline ends the VM rather than pausing it

The sandbox guide sets a default 15-minute timeout and an absolute 1,440-minute maximum from creation, including extensions. The disk disappears when the VM is destroyed unless state was exported or captured. Extending expires_at does not turn the temporary VM into an indefinite persistent computer.

Source 1 ↗

A full disk snapshot is a real feature, with a separate lifecycle

The current guide supports crash-consistent images of the VM filesystem, including installed packages, while the source keeps running. Restore boots a new VM with fresh processes; it does not resume RAM. Images expire after seven days, with three per account and one capture in flight. Source and restore sizes must match, and snapshot operations are currently REST-only.

Source 1 ↗

Wall-clock billing includes idle time

Metering starts at ready_at and ends at destruction, with no provisioning charge, rounding or minimum runtime. A VM waiting on a model costs the same as one executing. Credit exhaustion destroys running VMs, so a prepaid balance is also a lifecycle dependency; export important state before either deadline or balance exhaustion.

Source 1 ↗

Pricing

Compare billing models, then price your workload

CPU allocation, memory, billing minimums, disk, plan fees, and supported workload differ. These meters are not equal-performance machine quotes. Confirm region, resource units, and included allowances before estimating a total.

Sandbox as a Service

Pricing reviewed 2026-10-18

Small VM
$0.09/hour
2 vCPUs, 4 GB RAM and 40 GB disk; wall-clock time, billed by the second.
Rate source ↗
Medium VM
$0.28/hour
4 vCPUs, 8 GB RAM and 80 GB disk.
Rate source ↗
Large VM
$0.55/hour
8 vCPUs, 16 GB RAM and 160 GB disk.
Rate source ↗
New-account credit
$5 one-time credit
Prepaid top-ups do not expire; no subscription or seat fee.
Rate source ↗

Preserve the vendor’s GB labels. These VM rates do not establish the separate snapshot-storage rate: the lifecycle guide says deleting an image stops storage billing, but the reviewed billing page does not specify its amount. Include retained image charges when obtaining a full quote.

Check current Sandbox as a Service pricing ↗

Sandbox0

$0.015/GiB-hour compute (billed by the second at approximately $0.000004167/GiB-second), plus $0.02/GiB-month of retained incremental RootFS and memory checkpoint data. Shared base images and platform recovery retention are excluded; paused sandboxes accrue storage charges only.

Compute / GiB-hour
$0.015
Retained data / GiB-month
$0.02
Paused compute
$0.00

A 4 GiB agent, 100 running hours

$6.00 compute

4 GiB × 100 hours, billed by the second. Keeping 20 GiB of billable incremental data for a full billing month adds $0.40. CPU is derived from memory by the platform; choose a tier that fits your workload.

Understand storage billing →

Before migrating from Sandbox as a Service

  1. Export required files or create and verify a ready snapshot before timeout, deletion, credit exhaustion or the seven-day image expiry.
  2. Recreate system packages, configuration, commands, credentials and networking in the target template; account for fresh processes rather than converting a disk image into live memory.
  3. Test repeated returns to the same sandbox, growing installed tools and outputs, paused file operations and retained-storage costs alongside compute.

Common questions

Is Sandbox0 a drop-in Sandbox as a Service replacement?

Evaluate API compatibility and product scope. A shared sandbox category does not make SDKs, lifecycle semantics, or limits interchangeable.

Does keeping files also keep a running agent?

Filesystem state and volatile process state are separate. Sandbox0 requires explicit compatible memory checkpoints to preserve running processes; its default filesystem resume starts fresh processes.

Sources and review scope

The Boat team's Battleships directory is the discovery source. References below describe the product and plan discussed on this page. Check current availability, regional terms and billing units before migrating. Where the cited material does not establish a capability or price, the comparison identifies that uncertainty.

Battleships research record ↗sandbox-as-a-service.com/docs/sandboxes ↗sandbox-as-a-service.com/docs/billing ↗sandbox-as-a-service.com/pricing ↗Sandbox0 RootFS capacity →

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