box by ASCII
E2B alternative for AI agent sandboxes
E2B is strong when your product needs short-lived, programmatic sandboxes. box is built for a different shape: persistent Linux machines that coding agents can use like real developer environments.
Choose box when your agents need SSH access, Docker inside the VM, public networking, and a machine that can keep state across real development sessions.
What you get
Persistent VMs instead of throwaway sessions
A coding agent often needs more than a process sandbox. It needs dependencies, repo state, credentials, logs, build artifacts, background services, and a working shell that can be resumed. box gives each agent a full Ubuntu VM, so the environment can survive the shape of real software work.
Built for dev workflows
box includes SSH, Docker support inside the VM, GitHub CLI, common language runtimes, and a dedicated IPv4 per machine. That makes it a better fit for compile-heavy repos, multi-service apps, hosted previews, and agent workflows that look like normal engineering work.
Simple pricing for parallel agents
$20 buys 2M seconds, about 555 hours, of dedicated 4 vCPU / 8 GB VM-time. Use that on one machine or spread it across many agent VMs. The model is easy to reason about when you run parallel coding agents.
Which one should you use?
Use E2B when
you are building an app that needs short-lived per-user sandboxes, evals, RL-style rollouts, or very fast spawn-run-destroy cycles.
Use box when
you want agents to build software in real machines with SSH, Docker, networking, persistence, and simple CLI control.
Start a box VM
Install the CLI, create a machine, and run your agent in a full Linux environment.
curl -fsSL https://ascii.dev/api/box/install | sh