Skip to content
SPECIFICTION
Get listed

Firecracker

firecracker-microvm.github.io

Free plan LinuxAPISelf-hosted
Visit firecracker-microvm.github.io
Spec score 8.4 #5 of 22 in Server Virtualization Software

What it is

Firecracker is open-source virtualization software for running container and function workloads in lightweight microVMs. It uses Linux KVM hardware virtualization to isolate each workload and exposes only five emulated devices, a design intended to reduce attack surface. MicroVMs start in under 125 ms, add under 5 MiB of memory overhead each, and a host can create up to 150 per second while packing thousands onto one server. A RESTful API configures and starts the VMs, while rate limiters govern network and storage bandwidth and operations. The companion jailer adds Linux user-space security barriers. Firecracker supports Linux hosts and guests with kernel versions 4.14 and above, plus OSv guests, on production 64-bit Intel, AMD, and Arm CPUs with hardware virtualization. VM snapshots are supported, but GPU acceleration is not. It is free under Apache 2.0, with integrations including containerd, Kata Containers, and Fly.io.

Spec sheet

Purpose
Firecracker is open source virtualization technology for running secure, multi-tenant container and function workloads in lightweight microVMs.Read 7 Oct 2026 · firecracker-microvm.github.io
Free plan
YesRead 20 Sep 2026 · firecracker-microvm.github.io
Integrations
The site lists integrations including containerd, Kata Containers, E2B, Fly.io, Koyeb, Northflank, OpenNebula, Qovery, and microvm.nix.Read 7 Oct 2026 · firecracker-microvm.github.io
Support
The project directs community questions to its Slack workspace and GitHub repository issues.Read 7 Oct 2026 · github.com
Control API
A RESTful API controls the Firecracker process, including microVM configuration and startup.Read 7 Oct 2026 · firecracker-microvm.github.io
Density
Firecracker says a host can create up to 150 microVMs per second and pack thousands onto one server.Read 7 Oct 2026 · firecracker-microvm.github.io
GPU acceleration
NoRead 20 Sep 2026 · firecracker-microvm.github.io
Guest architecture
bothRead 20 Sep 2026 · firecracker-microvm.github.io
Host platforms
LinuxRead 20 Sep 2026 · firecracker-microvm.github.io
Isolation
Firecracker uses Linux KVM hardware virtualization to isolate microVM workloads.Read 7 Oct 2026 · firecracker-microvm.github.io
Jailer
The companion jailer applies Linux user-space security barriers as a second line of defense if the virtualization barrier is compromised.Read 7 Oct 2026 · firecracker-microvm.github.io
Minimal design
Firecracker exposes five emulated devices and says this reduces the attack surface of each microVM.Read 7 Oct 2026 · firecracker-microvm.github.io
Notable limitation
On aarch64, the pl031 RTC device does not support interrupts, so guest programs using an RTC alarm will not work.Read 7 Oct 2026 · github.com
Open source and license
Firecracker is open source and licensed under Apache 2.0.Read 7 Oct 2026 · firecracker-microvm.github.io
Operating systems
Firecracker supports Linux host and guest operating systems with kernel versions 4.14 and above, as well as OSv guests.Read 7 Oct 2026 · firecracker-microvm.github.io
Resource controls
Built-in rate limiters control network and storage resource use, including bandwidth and operations.Read 7 Oct 2026 · firecracker-microvm.github.io
Startup and memory
The site states that microVMs start in under 125 ms and have under 5 MiB of memory overhead per VM.Read 7 Oct 2026 · firecracker-microvm.github.io
Supported hardware
The site lists 64-bit Intel, AMD, and Arm CPUs with hardware virtualization support as generally available for production workloads.Read 7 Oct 2026 · firecracker-microvm.github.io
VM snapshots
YesRead 20 Sep 2026 · firecracker-microvm.github.io

Plans and prices

Firecracker VMM Free Open source · Apache 2.0 license Read 7 Oct 2026 · firecracker-microvm.github.io

Every Firecracker plan and price →

Strong points and limits

Strong points

  • Free, open-source Apache 2.0 license
  • MicroVM startup under 125 ms
  • Under 5 MiB memory overhead per VM
  • RESTful configuration and startup API
  • VM snapshots supported

Limits

  • No GPU acceleration
  • aarch64 RTC alarms do not work
  • Linux host and guest focus

Who it suits

It suits teams running isolated multi-tenant containers or functions on Linux infrastructure. It is also relevant to users needing API-controlled microVMs and high workload density.

Verdict

Firecracker specifies a compact virtualization model with clear performance, isolation, and control details. Check the aarch64 RTC limitation and Linux requirements before deployment.

Where Specifiction places it

Alternatives to FirecrackerAll alternatives →