Agent sandboxes / zipbox alternative

A Zipbox alternative for the agent computer behind the identity

Zipbox gives a coding agent a Linux microVM with a browser terminal, email, domain, and wallet identity. Pausing archives its disk and stops machine charges. It already preserves more than workspace files; compare disk growth, process expectations, and the surrounding application features before migrating.

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

When zipbox fits

Zipbox fits users who want a ready coding-agent computer with integrated identity, browser terminal, SSH, and platform-proxied model/API access. Email, domains, wallets, and agent skills are application features that a runtime API does not automatically replace.

When to consider Sandbox0

Consider Sandbox0 when building a hosted agent application around a durable complete writable RootFS with online automatic growth and supported file access while compute is paused. Supply the agent harness, user interface, identity integrations, and model routing that your product needs.

Capabilities

zipbox and Sandbox0: what persists?

Feature comparison with documentation and verification status
Environment and runtime lifetimezipboxNot established in this reviewSandbox0ttl 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 fileszipboxPause archives disk and restore boots the saved disk on fresh hardware. Deletion and held identity have different semantics.View evidence ↗Sandbox0The writable RootFS survives successful checkpoints, including software, system configuration, dependencies, and user data.Read documentation →
Whole RootFSzipboxThe retained artifact is the microVM machine disk rather than only a synchronized workspace.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 statezipboxDisk archive/restore with paused machine billing is documented; no RAM-continuity guarantee is 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 statezipboxThe guide describes disk archive and boot, not a supported retained-process memory contract.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.

Zipbox publishes fixed disk sizes by machine class. Its reviewed lifecycle guide establishes disk retention but not automatic online expansion of the complete mounted RootFS. Compare how the active agent handles package and output growth beyond its starting size.

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 →

A retained machine disk is different from a retained identity

Zipbox’s pause path archives the machine disk and restore boots it on fresh hardware. Reboot retains files but stops running work. Deletion removes the machine while its name, email, and wallet identity wait on hold. Identity continuity therefore does not prove filesystem retention after delete or continuation of the original process after restore.

Source 1 ↗

Machine size and access shape the workflow

The current rate card offers four fixed CPU/RAM/disk sizes, while larger sizes require discussion. The browser terminal permits one live owner session at a time. External SSH is IPv6-only under the reviewed access guide, so test the application’s connectivity and collaboration requirements rather than assume the same access surface on every runtime.

Source 1 ↗Source 2 ↗

The monthly figures illustrate always-on usage

Zipbox is prepaid without a subscription, meters running time by the second, and lists approximate always-on monthly totals beside hourly size rates. Paused boxes cost zero. Model calls through platform keys share the same balance and carry a published markup; using a matching own-provider key takes the direct provider-billing path.

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.

zipbox

Pricing reviewed 2026-10-18

Tiny
$0.0068 per running hour
1 vCPU, 2 GB RAM, 20 GB disk; about $5/month if always on.
Rate source ↗
Small
$0.0137 per running hour
2 vCPU, 4 GB RAM, 80 GB disk; about $10/month if always on.
Rate source ↗
Medium
$0.0274 per running hour
4 vCPU, 8 GB RAM, 160 GB disk; about $20/month if always on.
Rate source ↗
Paused boxes
$0
Rate source ↗
Platform-proxied LLM calls
Provider cost plus 3%
Shares the prepaid machine balance; matching own-provider keys bypass that metered proxy path.
Rate source ↗

Always-on monthly figures are approximations rather than a flat subscription or an unverified monthly cap. A positive balance is needed to boot. The one-time $25 signup credit requires a $5 top-up; it is not free recurring credit. Published machine prices exclude taxes and do not include arbitrary model/API usage.

Check current zipbox 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 zipbox

  1. Archive/export required machine files and record identity, email/domain, wallet, model-proxy, SSH, and agent workflow dependencies separately.
  2. Rebuild compatible tools in a Sandbox0 template, port command/file and lifecycle integration, and supply any identity or user-interface services the application needs.
  3. Validate repeated system changes, RootFS growth, paused file operations, process expectations, connectivity, and the full runtime plus model/API cost.

Common questions

Is Sandbox0 a drop-in zipbox 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 ↗zipbox.ai/docs/how-things-work ↗zipbox.ai/pricing ↗zipbox.ai/docs/access ↗zipbox.ai/docs/pricing ↗Sandbox0 RootFS capacity →

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