Application platforms / Server4Agent alternative

Server4Agent alternative

Server4Agent is a platform for asking an assistant to build and host private tools at stable project URLs. It retains project workspaces and supplies a build agent, deployment access controls and an engineering handoff. Those are application-platform features above the Linux execution layer.

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

When Server4Agent fits

Server4Agent fits teams that want to ship internal tools from chat or through MCP/REST, with private URLs, a browser IDE and project history. Retain that managed build-and-publish layer if it matches the customer workflow.

When to consider Sandbox0

Consider Sandbox0 when the required layer is a returning agent runtime with retained system packages, configuration and an automatically growing whole RootFS. You implement or retain the build agent, private-app routing, authentication and deployment UX separately.

Capabilities

Server4Agent and Sandbox0: what persists?

Feature comparison with documentation and verification status
Environment and runtime lifetimeServer4AgentNot 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 filesServer4AgentProject workspace and state persist between tasks and across idle scale-to-zero.View evidence ↗Sandbox0The writable RootFS survives successful checkpoints, including software, system configuration, dependencies, and user data.Read documentation →
Whole RootFSServer4AgentRetention of arbitrary system changes outside the documented project workspace is not established.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 stateServer4AgentIdle scale-to-zero with retained workspace is documented; this is not an established RAM checkpoint.View evidence ↗Sandbox0Pause compute between tasks; resume on available capacity. Default resume starts fresh processes from the saved filesystem.Read documentation →
Memory and process stateServer4AgentArbitrary process-memory capture/restore is not established.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.

Server4Agent explicitly retains the project workspace and offers stable hosted tools. Its reviewed docs do not establish automatic online growth or retention of the full Linux RootFS outside that workspace. Sandbox0 retains system installation and accumulated files across its supported lifecycle.

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.

Server4Agent exposes file/shell tools and a browser IDE, but the reviewed material does not establish full-RootFS read/write access while guest compute remains paused. An idle server scaling to zero is separate from the file API’s effective wake behavior.

See paused file operations →

Persistent project workspaces are part of the offer

The pricing FAQ says servers keep workspace and state between tasks and idle servers scale to zero. The product index places project files in a server workspace and offers browser VS Code plus project Git history. That is real persistence; the reviewed sources do not specify retention of arbitrary system paths outside the project workspace.

Source 1 ↗Source 2 ↗

Stable application delivery is separate from raw execution

An outer agent can provision a server and delegate a goal over MCP/REST, while the platform supplies the build workflow and a stable private-by-default project URL. Engineers can take over the same workspace later. Moving to another runtime requires preserving application ownership, secrets, routes and user authorization rather than only changing a command endpoint.

Source 1 ↗Source 2 ↗

Plan fees and included dollar credits are not the same amount

The pricing page defines one credit as $1 of metered compute/AI usage. Starter costs $29 with $10 included, and Pro $99 with $40 included. Paid plans can enter overage at approximately 1.2–1.4 times the base rate, while Free stops at its allowance; an account-wide budget cap is the published ceiling.

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.

Server4Agent

Pricing reviewed 2026-10-18

Free
$0; $2 trial credits
One server, 5 GB storage and one live public project; trial credit is not a recurring allowance.
Rate source ↗
Starter
$29/month including $10 credits
Two servers, 5 GB storage and three live public projects.
Rate source ↗
Pro
$99/month including $40 credits
Three servers, 20 GB storage and ten live public projects.
Rate source ↗
Paid usage beyond allowance
Approximately 1.2–1.4× base rate
Plan-dependent; the account-wide budget cap applies. Confirm the exact meters for your plan.
Rate source ↗

A server/project count is not an equal-resource CPU/RAM quote. Compute and AI share metered dollar credits, while subscription fees include other platform capabilities. Storage, public-project caps, private-app access and any enterprise bring-your-own-cloud terms differ by plan. Do not assume every dollar of the monthly fee becomes usage credit.

Check current Server4Agent 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 Server4Agent

  1. Inventory server/project IDs, workspace data, published routes, private/team access rules, secrets and effective budget/overage settings.
  2. Move compatible agent code and required files to Sandbox0, retaining or rebuilding the build/publish/authentication layer and stable application routes.
  3. Test engineering handoff, retained system paths, RootFS growth, paused files and full subscription, model, hosting and storage costs.

Common questions

Is Sandbox0 a drop-in Server4Agent replacement?

Evaluate API compatibility and product scope. These products serve different core workflows, so a change may require a different architecture.

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 ↗www.server4agent.com/pricing ↗www.server4agent.com/llms-full.txt ↗www.server4agent.com/docs/api ↗Sandbox0 RootFS capacity →

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