Agent sandboxes / Vercel Sandbox alternative

A Vercel Sandbox alternative for a growing agent computer

Vercel now supports persistent sandboxes through automatic filesystem snapshots, as well as mounted drives. For a long-lived agent, compare those storage mechanisms with the running root disk and the behavior of file calls after a session stops.

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

When Vercel Sandbox fits

Vercel Sandbox fits projects that want its SDK and project integration, automatic snapshot-backed sessions, and separately mounted drives. A long-lived sandbox can span multiple sessions, so its per-session timeout is not the total environment lifetime.

When to consider Sandbox0

Consider Sandbox0 when installing tools and growing the full Linux RootFS is the main workload. Paused Files API operations can inspect data without waking compute, and filesystem-only pauses also accept edits.

Capabilities

Vercel Sandbox and Sandbox0: what persists?

Feature comparison with documentation and verification status
Environment and runtime lifetimeVercel SandboxHobby: 45 minutes per session; Pro/Enterprise: 24 hours per session. Persistent sandboxes span multiple sessions.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 filesVercel SandboxAutomatic filesystem snapshots support persistent multi-session sandboxes.View evidence ↗Sandbox0The writable RootFS survives successful checkpoints, including software, system configuration, dependencies, and user data.Read documentation →
Whole RootFSVercel SandboxFilesystem restoration across sessions; drive data has a separate lifecycle.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 stateVercel SandboxA stopped persistent sandbox starts a new session from its filesystem snapshot.View evidence ↗Sandbox0Pause compute between tasks; resume on available capacity. Default resume starts fresh processes from the saved filesystem.Read documentation →
Memory and process stateVercel SandboxNot established in this reviewSandbox0Experimental 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.

A Vercel drive can provide larger mounted storage, while the runtime’s local root disk has its own capacity. Compare that split with Sandbox0’s automatic growth of the writable RootFS itself.

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.

Vercel’s persistent-sandbox SDK automatically resumes a stopped session for operations that need the VM. Retrieving a handle alone does not wake it; that is separate from reading or modifying persistent file contents.

See paused file operations →

A persistent sandbox outlives one Vercel session

Current Vercel persistence restores a stopped sandbox from its saved filesystem into a new session. Session duration limits apply to each boot. Configure snapshot expiry and retention; an expired source snapshot can require a new environment rather than a resume.

Source 1 ↗

A drive and the root disk have different jobs

Vercel publishes a 64 GB ephemeral disk for current SDK/custom-image runtimes, plus separate persistent-drive capacity and operation meters. A larger mounted drive expands a selected directory; assess where system packages and unmounted paths accumulate.

Source 1 ↗Source 2 ↗

File calls can wake a stopped Vercel sandbox

Vercel documents automatic resume when SDK operations such as writeFiles need a running VM. Sandbox0 routes supported paused Files API operations to persistent storage without resuming compute. That matters when your application inspects or stages files between agent turns.

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.

Vercel Sandbox

Pricing reviewed 2026-10-18

Active CPU in iad1
$0.128 per active CPU-hour
Rate source ↗
Provisioned memory in iad1
$0.0212 per GB-hour
Compute has a one-minute billing minimum; preserve GB units when comparing rates.
Rate source ↗
Snapshot storage
$0.08 per GB-month
Rate source ↗
Drive storage in iad1
$0.05 per GB-month
Drive reads are $0.0015/GB and writes $0.004/GB; regional rates vary.
Rate source ↗
Sandbox creations
$0.60 per million
Rate source ↗

Pro includes a $20 monthly Sandbox credit. Check plan fees, per-session limits, concurrency, snapshot retention, drive quotas, and regional prices. GB is not silently converted to GiB in this comparison.

Check current Vercel Sandbox 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 Vercel Sandbox

  1. Export the latest filesystem snapshot and every mounted drive separately, and record snapshot expiration settings.
  2. Map Vercel project authentication, SDK calls, ports, and network policy to Sandbox0 equivalents.
  3. Verify that background services restart after filesystem-only resume, and test file reads and writes while compute remains paused.

Common questions

Is Sandbox0 a drop-in Vercel Sandbox 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 ↗vercel.com/docs/sandbox/concepts/persistent-sandboxes ↗vercel.com/docs/sandbox/pricing ↗vercel.com/docs/sandbox/concepts/drives ↗/docs/sandbox/files ↗Sandbox0 RootFS capacity →

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