Sub-millisecond VM sandboxes for AI agents via copy-on-write forking

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Try it

curl -X POST https://api.zeroboot.dev/v1/exec \
  -H 'Content-Type: application/json' \
  -H 'Authorization: Bearer zb_demo_hn2026' \
  -d '{"code":"import numpy as np; print(np.random.rand(3))"}'

Benchmarks

Metric	Zeroboot	E2B	microsandbox	Daytona
Spawn latency p50	0.79ms	~150ms	~200ms	~27ms
Spawn latency p99	1.74ms	~300ms	~400ms	~90ms
Memory per sandbox	~265KB	~128MB	~50MB	~50MB
Fork + exec (Python)	~8ms	-	-	-
1000 concurrent forks	815ms	-	-	-

Each sandbox is a real KVM virtual machine with hardware-enforced memory isolation.

How it works

  Firecracker snapshot ──► mmap(MAP_PRIVATE) ──► KVM VM + restored CPU state
                              (copy-on-write)         (~0.8ms)

1. Template (one-time): Firecracker boots a VM, pre-loads your runtime, and snapshots memory + CPU state
2. Fork (~0.8ms): Creates a new KVM VM, maps snapshot memory as CoW, restores all CPU state
3. Isolation: Each fork is a separate KVM VM with hardware-enforced memory isolation

SDKs

Python — sdk/python

from zeroboot import Sandbox
sb = Sandbox("zb_live_your_key")
result = sb.run("print(1 + 1)")

TypeScript — sdk/node

import { Sandbox } from "@zeroboot/sdk";
const result = await new Sandbox("zb_live_your_key").run("console.log(1+1)");

Docs

• API Reference
• Deployment Guide
• Architecture

Status

Working prototype. The fork primitive, benchmarks, and API are real, but not production-hardened yet. Open an issue if you're interested.

Self-host or managed

Zeroboot is open source. Self-host it on any Linux box with KVM, or use the managed API:

curl -X POST https://api.zeroboot.dev/v1/exec \
  -H 'Content-Type: application/json' \
  -H 'Authorization: Bearer zb_demo_hn2026' \
  -d '{"code":"import numpy as np; print(np.random.rand(3))"}'

Building the managed service for teams that don't want to run their own infra. Sign up for early access: https://tally.so/r/aQGkpb

Known limitations

• Forks share CSPRNG state from the snapshot. Kernel entropy is reseeded via RNDADDENTROPY but userspace PRNGs (numpy, OpenSSL) need explicit reseeding per fork. See Firecracker's guidance.
• Single vCPU per fork. Multi-vCPU is architecturally possible but not implemented.
• No networking inside forks. Sandboxes communicate via serial I/O only.
• Template updates require a full re-snapshot (~15s). No incremental patching.

License

Apache-2.0