Development environments / GitHub Codespaces alternative

A GitHub Codespaces alternative for an agent-owned computer

GitHub Codespaces gives developers a repository-centered dev container with editor and GitHub integrations. Ordinary stop/start preserves more than the repository workspace, while rebuild has a narrower retention boundary. Compare those operations and lifetime policies with an agent environment that evolves across tasks.

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

When GitHub Codespaces fits

Codespaces fits developer workflows that depend on GitHub repositories, dev container configuration, browser or VS Code access, organization policy, and prebuilds. Those collaboration and development-product features are separate from a generic agent runtime.

When to consider Sandbox0

Consider Sandbox0 when you operate an agent application and need a durable per-user RootFS, automatic online growth, and supported persistent-file access during compute pauses. Supply the repository/editor integration and workflow controls your users need.

Capabilities

GitHub Codespaces and Sandbox0: what persists?

Feature comparison with documentation and verification status
Environment and runtime lifetimeGitHub CodespacesActive codespaces have a 12-hour maximum before stop/restart; retained environment lifetime and idle/deletion policies are separate.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 filesGitHub CodespacesSaved files survive stop/start. /workspaces also survives container rebuild; other paths have a different rebuild boundary.View evidence ↗Sandbox0The writable RootFS survives successful checkpoints, including software, system configuration, dependencies, and user data.Read documentation →
Whole RootFSGitHub CodespacesOrdinary stop/start retains container system changes beyond /workspaces, excluding special temporary behavior. Rebuild clears those outside-workspace changes.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 stateGitHub CodespacesStop/start retains saved changes and stops compute billing; running processes do not continue.View evidence ↗Sandbox0Pause compute between tasks; resume on available capacity. Default resume starts fresh processes from the saved filesystem.Read documentation →
Memory and process stateGitHub CodespacesStopping ends running processes; saved terminal history does not preserve execution memory.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.

Codespaces machine-size and dev container configuration are distinct from automatic online growth of a durable whole RootFS. The reviewed lifecycle describes recreation and rebuild behavior rather than a complete live-RootFS growth contract.

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 →

Codespaces retains system changes across ordinary stop/start

GitHub documents that changes outside /workspaces, except the special temporary-file case, survive stop/start with the container. Rebuilding clears changes outside /workspaces, while the persistent workspace returns. Dev container setup and dotfiles can reconstruct tools, so keep that setup reproducible for rebuilds that clear system changes.

Source 1 ↗

An active session and the retained environment have different lifetimes

Codespaces automatically stops after a maximum 12-hour active lifetime even if work continues. Its normal idle timeout is 30 minutes, and stopped environments default to deletion after 30 inactive days, subject to configured policies. Stopping ends running processes but retains saved changes; reconnecting to a saved environment is not process-memory continuation.

Source 1 ↗

Included hours use machine multipliers, and storage keeps billing

Codespaces bills active compute and retained storage separately. Personal included compute is consumed with a multiplier equal to the machine’s core count, so 120 included units provide 60 wall-clock hours on a two-core machine. Stopped codespaces and prebuild artifacts still consume storage; organization ownership and payment rules determine who pays.

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.

GitHub Codespaces

Pricing reviewed 2026-10-18

Two-core active codespace
$0.18 per hour
Consumes included compute with a multiplier of 2.
Rate source ↗
Four-core active codespace
$0.36 per hour
Consumes included compute with a multiplier of 4.
Rate source ↗
Retained storage
$0.07 per GB-month
Includes applicable retained codespace and prebuild storage; continues while stopped.
Rate source ↗
GitHub Free personal allowance
120 included compute units and 15 GB-month storage per month
120 units equal 60 hours on a two-core machine, not 120 hours on every shape.
Rate source ↗
GitHub Pro personal allowance
180 included compute units and 20 GB-month storage per month
Allowance scope is personal accounts; organization-funded usage has its own billing rules.
Rate source ↗

Preserve the vendor’s GB storage units and per-machine core rates. Included usage is not a universal free organization tier or one allowance per repository. Prebuild generation can also consume GitHub Actions minutes. Compute, retained storage, organization policy, and ownership all affect the total.

Check current GitHub Codespaces 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 GitHub Codespaces

  1. Push/export required work and inventory devcontainer configuration, dotfiles, prebuilds, secrets, system changes, editor access, and organization policy.
  2. Build compatible agent tools in a Sandbox0 template and supply repository, user-interface, credential, command/file, and lifecycle integration.
  3. Test actual system paths across repeated tasks, rebuild requirements, long-running process behavior, RootFS growth, paused file access, and the correct compute/storage allowance model.

Common questions

Is Sandbox0 a drop-in GitHub Codespaces 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 ↗docs.github.com/en/codespaces/about-codespaces/deep-dive ↗docs.github.com/en/codespaces/about-codespaces/understanding-the-codespace-lifecycle ↗docs.github.com/en/billing/concepts/product-billing/github-codespaces ↗Sandbox0 RootFS capacity →

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