A sandbox is a virtual machine of its own: a Firecracker microVM that runs an OCI image, the kind docker builds and registries serve. You make one with an API call. Then you run commands in it, read and write its files, open a terminal or a link to one of its ports. Commands and files reach it through an agent inside the machine, not through its network.
When nothing happens in it, a sandbox sleeps. It keeps its memory, its processes and its disk, and the next call wakes it where it was, in milliseconds. It stays until you delete it.
When to use Sandbox
- An AI agent’s computer: a coding agent, a browser agent or a code interpreter that runs commands, installs packages and keeps its work between turns.
- Code you did not write: what users or models send you, kept away from your own machines and from each other, with network rules and secrets the code never sees.
- A job per request:
glac runmakes a sandbox, runs one command and deletes it. - Environments that branch: a snapshot of a running sandbox, and copies (forks) that each go on from that moment.
- A server of its own: with
init: "systemd"the image’s own systemd is its PID 1, for packages, services, cron and SSH as on any server (a whole system).
To serve an image at an address, with instances that start for requests, use Cube. Both run on the same machines, at the same prices.
How it works
- Make.
POST /v1/sandboxes(glac sandboxes create) with an image, or with none for the platform’s default image. The first sandbox of an image waits while the platform pulls it and saves a template. Later ones are copies of that template, from a pool that is already running. - Use. Run commands (
exec), read and write files, open a terminal, give out links to ports. Calls wait for a sandbox that is starting or asleep: none fails for that. - Sleep. After
sleep_after_secondsidle (30 unless you say), it sleeps. Whatever needs it wakes it: a command, a file, a request on a link, a timer.
What it costs
A sandbox pays for the CPU it uses and the memory it holds while it is awake. Asleep, it pays for what it keeps: its memory and the part of its disk that is its own. One held paused in the machine’s memory pays for that memory as if awake, and no CPU.
| Meter | Price | Free, each day | Paid includes a month |
|---|---|---|---|
| CPU, while it computes | $0.01 a million CPU-ms | 1M CPU-ms | 60M CPU-ms |
| Memory, while awake or paused in memory | $0.008 a GiB-hour | 6 GiB-hours | 250 GiB-hours |
| Requests, into Cubes and through sandbox links | $0.30 a million | 100,000 | 10 million |
| What a sleeping instance keeps (its memory and its own disk) | $0.02 a GB-month | 15 GB of data in all, with snapshots and Drives | 20 GB-months of data, with snapshots and Drives |
| What snapshots keep | $0.02 a GB-month | The same data | The same data |
| Traffic out to the internet, from North America | $0.004 a GB | 3 GB, from any region | 1 TB, from any region |
| Traffic out to the internet, from Europe | $0.004 a GB | ||
| Traffic out to the internet, from Asia-Pacific | $0.01 a GB |
A paid plan includes no quantity of a meter: its fee comes back as the same amount of credit, which pays for any meter at these prices. See pricing and plans.
Limits of each plan
| Free | Paid | |
|---|---|---|
| Largest instance | 2 vCPUs, 4 GiB | 8 vCPUs, 16 GiB |
| Instances awake at once | 5 | 500 |
| Their vCPUs together | 10 | 500 |
| Their memory together | 10 GiB | 1,000 GiB |
| Sleeping instances kept | 20 | 10,000 |
| Sandboxes made a minute | 10 | 600 |
| Sandboxes one project makes an hour | 200 | 10,000 |
The sandboxes awake, their vCPUs and their memory are counted for the whole account: sandboxes and Cubes’ instances of every project together. Every limit is on the limits page.
Next
- Quickstart: make a sandbox, run a command, copy files, open a port, with the command line, Python or the console.
- Commands, files and terminals: running commands, their output, files, terminals, images.
- Sleep and wake: what puts a sandbox to sleep, what wakes it, keeping it awake from inside.
- Snapshots and forks: saving a sandbox as it is, going back, copies that go on, templates.
- Links, tokens and SSH: links to ports, tokens for one sandbox, SSH.
- Network rules and secrets: what a sandbox may reach, and secrets it uses without holding them.