Run untrusted code in hardened VMs.

Hotcell runs code inside tiny virtual machines. Each execution gets its own kernel, its own memory, its own process tree. The code cannot see or touch the host because it is running on separate virtual hardware.

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terminal — hotcell cli

$ hotcell run alpine -- echo "hello from a VM"
hello from a VM

$ hotcell run --network inet python:3.12-slim \
    -- python3 -c "import urllib.request; \
       print(urllib.request.urlopen( \
         'http://example.com').status)"
200

EXIT: 0

security

VM Isolation

Each execution gets its own kernel, memory space, and process tree. Three pluggable VMM backends — libkrun (macOS + Linux), Firecracker (Linux), and Cloud Hypervisor (Linux) — provide hardware-level virtualization. 22 hardening items across host and guest: seccomp BPF with TSYNC, Landlock MAC, 5-namespace isolation, capability dropping, cgroup v2 limits, vsock HMAC-SHA256 authentication, network egress filtering, and fs-verity/dm-verity for rootfs integrity.

Libkrun

Firecracker

Cloud Hypervisor

Hypervisor.framework

KVM

inventory_2

OCI Image Support

No special image format. Pull any Docker/OCI image, run it in a VM.

stream

Real-Time Streaming

Stream console output in real-time via SSE or WebSocket. Output streams as the VM runs.

swap_horiz

Pluggable Backends

Choose your VMM per-request. libkrun for macOS + Linux with virtiofs and TSI networking. Firecracker for stronger Linux isolation with ext4 block devices. Cloud Hypervisor for Linux with virtio-fs and a REST API over Unix socket.

devices

Dual-Platform

macOS (Apple Silicon via Hypervisor.framework) and Linux (x86_64/aarch64 via KVM). Native hypervisors for zero-overhead performance.

<200ms VM Boot

3 VMM Backends

0 Docker

Ready to try Hotcell?

Hotcell is a CLI, Rust library, and HTTP server for running code in hardware-isolated VMs. Three pluggable VMM backends, real-time streaming, and a defense-in-depth security model with 22 hardening items.

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