Agent sandboxes / Instabox alternative

An Instabox sandbox alternative for a growing persistent computer

Instabox offers cloud machines that retain installed software and files, with memory pause and separate disk-only named snapshots. Its current hosted service has fixed machine sizing and temporary free terms, which should be evaluated separately from a future paid rate card.

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

When Instabox fits

Instabox fits teams evaluating persistent development machines, Docker, agent sign-ins, SSH, desktop access, and reusable prepared snapshots. Its current free machine allowance makes small trials possible without assuming future commercial rates.

When to consider Sandbox0

Consider Sandbox0 when the agent needs an automatically growing writable RootFS and supported persistent-file access while compute stays paused. Select filesystem-only or compatible experimental memory pause deliberately for the application’s process-continuity needs.

Capabilities

Instabox and Sandbox0: what persists?

Feature comparison with documentation and verification status
Environment and runtime lifetimeInstaboxExecution timeout can be cleared; the inactivity pause policy is separate and can be disabled.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 filesInstaboxMachine files and installed software survive pause and stop; deletion removes the machine.View evidence ↗Sandbox0The writable RootFS survives successful checkpoints, including software, system configuration, dependencies, and user data.Read documentation →
Whole RootFSInstaboxInstalled system software and /data state can be retained; root-only named snapshots deliberately omit home/workspace files.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 stateInstaboxPause/resume can retain processes but may start fresh if memory restore is unavailable.View evidence ↗Sandbox0Pause compute between tasks; resume on available capacity. Default resume starts fresh processes from the saved filesystem.Read documentation →
Memory and process stateInstaboxPause has a memory-preserving path; named snapshots explicitly exclude memory and processes.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.

Instabox’s SDK describes grow-only root-disk sizing, but its hosted API currently rejects custom resource sizes. The reviewed hosted contract does not establish automatic online RootFS expansion 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.

Instabox can list files in a saved snapshot without starting a machine. File access to an automatically paused machine can resume it; this differs from Sandbox0’s supported paused Files API, which leaves compute paused.

See paused file operations →

Named snapshots and memory pause are distinct artifacts

Instabox pause keeps files and attempts to keep processes; the machine guide permits a fresh start if memory restoration is unavailable. Named snapshots instead save installed software and /data files without RAM or running processes. Root-only snapshots intentionally omit home and workspace data.

Source 1 ↗Source 2 ↗Source 3 ↗

Hosted sizing is narrower than the general SDK surface

The SDK describes CPU, memory, data-disk, and root-disk fields, but explicitly says api.instabox.sh currently rejects custom resource fields. Hosted machines use the fixed size shown in the limits guide. A possible SDK root-disk growth field is not proof of an available hosted autoscaling feature.

Source 1 ↗Source 2 ↗

Current free access is not a future price guarantee

The public price page currently offers five free machines and says pricing is still being determined. Paused and stopped machines count toward the machine allowance, and storage and snapshot quotas can prevent new creates. Confirm commercial terms and effective quotas before planning a large returning-user fleet.

Source 1 ↗Source 2 ↗

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.

Instabox

Pricing reviewed 2026-10-18

Current hosted preview allowance
$0 for up to five machines
The price page describes current free access while future pricing is being determined.
Rate source ↗
Current hosted machine size
4 vCPUs and 8 GiB RAM in the limits guide
The pricing page uses an 8 GB label; verify effective byte units and account limits.
Rate source ↗
Future paid rates
Not published as a fixed offer
Rate source ↗

Do not extrapolate temporary free access into a permanent zero-cost commitment. The current limits guide counts paused/stopped machines and lists ten snapshots and a 200 GB aggregate storage allowance. General SDK resource fields do not override the hosted service’s fixed-size restrictions.

Check current Instabox 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 Instabox

  1. Save the appropriate named snapshot and export essential files before deletion; distinguish full data snapshots from root-only snapshots and retained RAM.
  2. Port image setup, sign-ins and credentials, Docker-dependent tools, SSH and desktop requirements, and timeout policy into the intended runtime integration.
  3. Validate repeated installed-package state, RootFS growth, paused file access, process fallback behavior, and effective hosted terms beyond the preview allowance.

Common questions

Is Sandbox0 a drop-in Instabox 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 ↗instabox.sh/docs/concepts ↗instabox.sh/docs/machines ↗instabox.sh/docs/snapshots ↗instabox.sh/docs/sdk ↗instabox.sh/docs/limits ↗instabox.sh/pricing ↗Sandbox0 RootFS capacity →

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