# GitHub Codespaces vs an agent sandbox: which one should run AI agents?

Runtime Cloud (withruntime.com) charges $0.03125 an hour while idle. Codespaces is for people.

## Which should you use, GitHub Codespaces or an agent sandbox?

It depends on who drives the machine, a person or a program. For programs, such as an agent that needs a fresh machine per task, Runtime offers that kind: $0.03125 an hour while a 2 vCPU, 4 GiB sandbox waits, and $0.08 when busy. That is below a 2-core codespace's hourly rate. Commands return structured results. Pick Codespaces for people: a developer, a class or a reviewer who wants a ready editor for a repository, inside GitHub's billing and its free monthly hours.

## What Codespaces is built for

GitHub describes a codespace as a development environment for a repository.
When you create one, "a virtual machine (VM) is created", "dedicated and
private to you", and "GitHub Codespaces uses a Docker container as the
development environment". You connect to it with an editor, or from a
terminal with `gh codespace ssh`.

- **Files.** `/workspaces` is "a persistent directory that is mounted into the
  container". Changes elsewhere survive a stop and start but "are not preserved
  when you rebuild the container".
- **Idle timeout.** "By default this period is 30 minutes", and it can be set
  from 5 to 240 minutes.
- **Retention.** Stopped codespaces are deleted after 30 days inactive by
  default, and 30 days is the maximum.
- **API.** The REST API creates a codespace in a repository and starts and
  stops it (`POST /repos/{owner}/{repo}/codespaces`,
  `POST /user/codespaces/{codespace_name}/start`). Commands inside run over a
  connection such as `gh codespace ssh`.

## Side by side

|               | GitHub Codespaces                            | Runtime sandbox                                                                                  |
| ------------- | -------------------------------------------- | ------------------------------------------------------------------------------------------------ |
| Made for      | A developer working on one repository        | Code that an agent or a program starts, runs and throws away                                     |
| Machine       | A dedicated VM with the dev container inside | A Firecracker microVM with its own Linux kernel                                                  |
| Run a command | Connect, then run it                         | `sbx.exec(...)`, with exit code, output and a timeout in the result                              |
| Sizes         | 2 to 32 cores                                | Up to 16 vCPUs and 64 GiB (paid), set per sandbox; 2 vCPU and 4 GiB by default |
| Idle          | Stops after 5 to 240 minutes; files kept     | Pauses with files, memory and running processes, kept while you have credit                      |
| Copies        | New codespaces from the repository           | Fork a running sandbox, memory included, into 1 to 100 copies                        |
| Editor        | An editor, or `gh codespace ssh`             | VS Code and JetBrains over SSH (`runtime sandboxes ssh config --install`)                        |
| Billing       | By machine type while running, plus storage  | Measured CPU plus reserved memory while running; paused storage                                  |

## What each costs

GitHub's rates, checked 26 October 2026: compute from $0.18 an hour on a
2-core machine to $2.88 on 32 cores, "proportional to the number of processor
cores", and storage at $0.07 per GB-month. A personal account on GitHub Free
includes 120 core hours of compute, 60 hours on a 2-core machine, and 15
GB-month of storage a month. GitHub Pro includes 180 core hours and 20
GB-month.

Runtime at 2 vCPU and 4 GiB: $0.03125 an hour waiting (memory plus a CPU floor
of a twentieth of a vCPU) and $0.08 an hour with both CPUs busy.

| Usage, past any free allowance     | Codespaces, 2-core   | Runtime, 2 vCPU and 4 GiB                                                                      |
| ---------------------------------- | -------------------- | ---------------------------------------------------------------------------------------------- |
| One hour                           | $0.18                | $0.03125 waiting, $0.08 busy                                                      |
| A working month, 8 hours × 21 days | 168 × $0.18 = $30.24 | 168 × $0.03125 = $5.25 to 168 × $0.08 = $13.44 |
| Stored while idle                  | $0.07 per GB-month   | $0.08 per decimal GB-month, memory included                                  |

Most of an hour, an agent waits on its model. Measured CPU bills that wait at the
floor, not for two idle cores ([pricing](/docs/pricing)).

## The Runtime equivalent

A named environment per task or per user. It is found again if it exists, paused
after 15 quiet minutes, and woken by the next command.

```ts check
import { Sandbox } from "withruntime";

const dev = await Sandbox.getOrCreate("issue-4821", { idlePauseSeconds: 900 });
await dev.exec("git clone https://github.com/octocat/Hello-World.git repo || true", {
  timeoutMs: 120_000,
});
const run = await dev.exec("cd repo && git log --oneline -1");
console.log(run.stdout);
```

```python check
from withruntime import Sandbox

dev = Sandbox.get_or_create("issue-4821", idle_pause_seconds=900)
dev.exec("git clone https://github.com/octocat/Hello-World.git repo || true", timeout_ms=120_000)
print(dev.exec("cd repo && git log --oneline -1").stdout)
```

To look over the agent's shoulder in your own editor:

```bash no-run
runtime sandboxes ssh config --install   # then connect VS Code to issue-4821.runtime
```

## Which one fits

- **Pick Codespaces** for people: a developer, a class or a reviewer who
  wants a ready editor for a repository, inside GitHub's billing and its free
  monthly hours.
- **Pick an agent sandbox** for programs: an agent that needs a fresh machine
  per task, a hundred at the same time, commands with structured results, network rules
  it cannot change, keys it never holds, and a bill that stays small while it waits on the model.

More: [coding agent sandbox](/use-cases/coding-agent-sandbox),
[per-user dev environments](/use-cases/per-user-dev-environments),
[pause and resume a sandbox](/how-to/pause-and-resume-a-sandbox),
[SSH and editors](/docs/editors).

## Runtime Cloud

Runtime charges $0.03125 to $0.08 an hour for 2 vCPUs and 4 GiB, against
$0.18 an hour for a 2-core codespace. Runtime bills the CPU the code uses, not the
machine's cores. Every command is one API call. GitHub rates were checked 25 October 2026.

A paid Runtime account runs 100 sandboxes at the same time. New accounts get
100 free hours of a 1 GB machine in the first 30 days, with no card.

To start, run `npx withruntime login`. The [migration guide](/docs/migrate) helps if your agent already uses another sandbox provider.

## Sources

Checked 26 October 2026.

- [GitHub: Codespaces billing](https://docs.github.com/en/billing/concepts/product-billing/github-codespaces) and [GitHub's plans](https://docs.github.com/en/get-started/learning-about-github/githubs-plans)
- [GitHub: Codespaces deep dive](https://docs.github.com/en/codespaces/about-codespaces/deep-dive)
- [GitHub: timeout period](https://docs.github.com/en/codespaces/setting-your-user-preferences/setting-your-timeout-period-for-github-codespaces) and [automatic deletion](https://docs.github.com/en/codespaces/setting-your-user-preferences/configuring-automatic-deletion-of-your-codespaces)
- [GitHub: Codespaces REST API](https://docs.github.com/en/rest/codespaces/codespaces), [gh codespace ssh](https://cli.github.com/manual/gh_codespace_ssh)
- Runtime [pricing](/docs/pricing), [speed](/docs/speed) and [SSH and editors](/docs/editors)

Facts on this page were checked on 26 October 2026.