Agent sandboxes / Celesto Cloud alternative

A Celesto sandbox alternative for an agent that outgrows a fixed root disk

Celesto’s current price page describes prepaid computers with an included fixed root disk and free stopped-disk retention for 30 days. Its older computer guides describe a different size and persistence configuration. Use the effective current offer when choosing how a user’s agent returns to saved state.

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

When Celesto Cloud fits

Celesto fits teams that want its computer-use integrations, computer SDK, ready templates, and prepaid shape-based running costs. Shared CPU classes and available host capacity are part of the offer; verify the current image, resource shape, and API behavior you plan to use.

When to consider Sandbox0

Consider Sandbox0 when the durable writable RootFS should expand automatically online as tools and outputs grow, and supported persistent-file operations should work while compute stays paused. Configure explicit retention and deletion policies for the user’s environment.

Capabilities

Celesto Cloud and Sandbox0: what persists?

Feature comparison with documentation and verification status
Environment and runtime lifetimeCelesto CloudNot 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 filesCelesto CloudThe current offer retains stopped root disks free for 30 days; existing machines retain their original rate.View evidence ↗Sandbox0The writable RootFS survives successful checkpoints, including software, system configuration, dependencies, and user data.Read documentation →
Whole RootFSCelesto CloudThe published retained artifact is the included root disk for the OS and tools, not merely project files. Verify image-specific paths and retention.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 stateCelesto CloudStop/start is documented; current price page separately describes retained stopped disks.View evidence ↗Sandbox0Pause compute between tasks; resume on available capacity. Default resume starts fresh processes from the saved filesystem.Read documentation →
Memory and process stateCelesto CloudThe reviewed public offer does not establish a general 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.

The latest price page includes fixed root disks by size. The reviewed guides do not establish automatic online expansion of the complete root disk. Separate workspace-storage scalability from operating-system and tool capacity.

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 root disk is more than a saved workspace

The current rate card includes a fixed operating-system/tool disk for each computer and says stopped root disks are retained free for 30 days. The older resource guide also distinguishes root storage from workspace storage. This is not evidence that Celesto only saves a workspace; verify complete retained paths and the effective image lifecycle.

Source 1 ↗Source 2 ↗

Current pricing and older SDK examples do not describe the same sizes

The current price page lists Micro through XL, with root disks from 20 to 100 GB. Older docs use Nano/Builder/Growth plan names and different RAM/disk bounds, plus a create-time persistent-home option. Do not combine the old plan limits with new rates or promise that an older SDK flag has unchanged semantics.

Source 1 ↗Source 2 ↗Source 3 ↗

Prepaid running time and stopped retention have separate boundaries

The current offer has no monthly platform fee, accepts top-ups above $2, and stops computers when funds are too low. New sandboxes use the advertised rates, while existing sandboxes retain their original rates even after stop/restart. The 30-day free stopped-root-disk statement is a retention boundary, not an unlimited archival promise.

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.

Celesto Cloud

Pricing reviewed 2026-10-18

Micro
$0.015 per running hour
1 shared vCPU, 2 GB RAM, 20 GB fixed root disk.
Rate source ↗
Small
$0.020 per running hour
1 shared vCPU, 4 GB RAM, 25 GB fixed root disk.
Rate source ↗
Large
$0.080 per running hour
4 shared vCPUs, 16 GB RAM, 60 GB fixed root disk.
Rate source ↗
Platform fee
No monthly platform fee
Prepaid top-up must be above $2; the page gives $2.01 as the minimum example.
Rate source ↗
Stopped root disk
Retained free for 30 days
Rate source ↗

These rates apply to newly created sandboxes. Existing rates can differ, and shared-vCPU shapes do not establish equal hardware performance. The one-time trial is $5 runtime credit valid 30 days for a retained Micro; it is not a monthly allowance. Confirm effective SDK limits because older documentation conflicts with the current rate card.

Check current Celesto Cloud 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 Celesto Cloud

  1. Record the source computer’s actual image, rate, disk and persistent-home settings; export essential state before stopped-disk retention ends.
  2. Recreate tools in a Sandbox0 template and port computer commands, files, ports, credentials, network policy, and any computer-use integrations.
  3. Validate required paths after repeated tasks, online RootFS growth, paused file operations, process requirements, and the effective current prepaid charges.

Common questions

Is Sandbox0 a drop-in Celesto Cloud 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 ↗celesto.ai/pricing ↗docs.celesto.ai/cloud/features/resources ↗docs.celesto.ai/cloud/computers ↗Sandbox0 RootFS capacity →

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