Coding agent attempts
Prepare a repository once, fork parallel solutions and run each test suite independently.
Sandbox infrastructure for AI agents
AI sandboxespriced like infrastructure.
Spawn an isolated environment in under 120ms. Fork it for parallel work, destroy it when done, and pay from $0.024/hour.
How warm starts work →01Box lifecycle
Spawn a box.
Five commands. The whole lifecycle.
The CLI creates box1, forks four linked child boxes, pauses and resumes the parent, then destroys the entire disposable fleet.
See how it worksLIVE / BOX LIFECYCLE
- 01Spawn
Start a clean microVM for one agent task or untrusted command.
- 02Fork
Branch a prepared sandbox into parallel attempts without repeating setup.
- 03Pause
Freeze CPU while preserving the process, memory and filesystem state.
- 04Resume
Continue the same workload exactly where the sandbox stopped.
- 05Kill
Reclaim compute, network and disposable state when the work ends.
A lower bill you can inspect.
Continuously active scenario: 12,000 hours (50 sandboxes × 240 h), 4 vCPU / 8 GB RAM.
MONTHLY BILL / LIVE COMPARISON12,000 HOURS / 4 VCPU / 8 GB RAM
HEIGHT / NORMALIZED COSTINSIDE CUBE / × VS SPAWNDTOP / MONTHLY PRICE
MAX PLAN / INCLUDED POOL + $0.050 OVERAGEView pricing methodology →
Directional estimate, not a quote. The comparison models continuously active 4 vCPU / 8 GB sandboxes at published May 2026 rates. Plans, minimums, storage, networking and regions differ; active-CPU pricing may produce lower bills for I/O-heavy workloads.
Control every box from CLI, API, SDK or MCP.
Call the lifecycle from your terminal, control plane or agent runtime—or let Claude operate boxes through MCP.
$
03Control + MCP
Start in the terminal. Stay in your stack.
Use the CLI directly, call the lifecycle over HTTP, bring it into your code with the TypeScript SDK or let Claude operate boxes through MCP.
Explore the interfacesUntrusted code gets its own machine.
Every sandbox is a Firecracker microVM with its own network namespace. Kill reclaims the VM, network and disposable state.
FIRECRACKER / GUEST BOUNDARYSTATIC MODEL / PER SANDBOX
- VM / HARDWARE BOUNDARY
- Each sandbox runs as its own Firecracker microVM, not as a shared process container.
- NETWORK / PER SANDBOX
- A dedicated network namespace and tap device separate the guest from the host and other boxes.
- STATE / EXPLICIT
- Memory and disk persist only when you pause or create a named snapshot.
- KILL / TERMINAL
- Kill reclaims compute, network and disposable state, and stops billing.
WHAT RUNS HERE
Generated code execution
Run untrusted commands and collect stdout, stderr and exit status through the API.
Human-in-the-loop jobs
Pause while an agent waits for approval, then resume with its process state intact.
Preview environments
Expose an application port and share the resulting sandbox URL.
Start free. Scale by the second.
Every plan includes a monthly pool of hours. Smaller sandboxes consume it more slowly.
Free
$0Included pool24 hours
Effective rateIncluded
Overage rate$0.050 / hour
Get started Pro
$21 / monthIncluded pool556 hours
Effective rate$0.038 / hour
Overage rate$0.050 / hour
Choose Pro Max
$97 / monthIncluded pool4,000 hours
Effective rate$0.024 / hour
Overage rate$0.050 / hour
Choose Max RATE SHOWN ABOVEEnterprise
CustomIncluded poolCustom hours
Effective rateVolume pricing
Overage rate$0.050 / hour
Contact us Optional overage starts after the included pool is exhausted · 1 hour = 1 hour on a 4 vCPU / 8 GB RAM sandbox; smaller sizes consume hours proportionally.Read the billing model →
06 / START
Start with one sandbox.
No credit card. 24 hours included.
$
spawn create baseWARM / <120MS