Firecracker vs gVisor

Firecracker gives each sandbox a microVM with its own kernel. gVisor gives each sandbox a kernel that runs in user space. Both keep sandbox code away from the host kernel.

Updated Oct 13, 2026

Firecracker

A virtual machine monitor from AWS.

Type: MicroVM
Own kernel
Used by: Lizard Sandboxes, Mosaic Sandbox, Oblien Workspace, CreateOS Sandbox, DigitalOcean Harness Runtime, Together Sandbox, Declaw, E2B, HopX, InstaVM, Leap0, Superserve, Thunder Sandboxes, PandaStack Sandbox, LangSmith Sandboxes, Caged, Cloudflare Sandbox, AWS Lambda MicroVMs, Deno Sandbox, Vercel Sandbox, Maritime, OmniRun, RemoteHost, Unikraft Cloud

What is Firecracker?firecracker-microvm.github.io

gVisor

An application kernel from Google.

Type: User-space kernel
Own kernel: In user space
Used by: Agent37 Cloud, Bunny Sandbox, Cua Fleets, Modal, Sandbox0

What is gVisor?gvisor.dev

How they differ

6 fields, side by side

Field

Firecracker

gVisor

Kind: Firecracker: Virtual machine monitor; gVisor: Application kernel
Kernel: Firecracker: Own guest kernel for each sandbox; gVisor: Host kernel behind a user-space kernel
Made by: Firecracker: AWS; gVisor: Google
Written in: Firecracker: Rust; gVisor: Go
License: Firecracker: Apache-2.0; gVisor: Apache-2.0
Needs hardware virtualization: Firecracker: Yes (KVM); gVisor: No

When the difference matters

A microVM puts a guest kernel between the sandbox and the host, so a fault in the guest kernel does not reach the host. A user-space kernel needs no hardware virtualization, so it works where virtual machines are not available. You do not choose between them directly. You choose a provider, and the provider has chosen one.