Firecracker alternatives
The 6 alternatives below are grouped by kind of sandbox, and each says what it does differently from Firecracker. Start from whatever made you look: missing GPUs, session limits, self-hosting, pricing or isolation.
Why teams look beyond Firecracker
The reference microVM primitive for sandbox platforms; choose it when you are building a platform rather than consuming one.
- Requires KVM and hardware virtualisation on the host, so it does not run on macOS or inside most cloud VMs without nested virtualisation
- No GPU passthrough or graphics device
- A VMM only: you must provide guest kernels, root filesystems, networking and a control plane yourself
- Snapshots must be restored on an identical hardware and software configuration, and network connections are not guaranteed to survive a resume
Firecracker alternatives, by kind
Hosted sandbox platforms
SDK-driven sandboxes you create, run code in and destroy through an API.
E2B
Open-source cloud sandboxes for AI agents, each a Firecracker microVM, with pause/resume, snapshots and forking.
- Firecracker microVM
- Open source
- Self-hostable
- BYOC
- Pause/resume
How it differs: Code interpreters and short-to-medium-lived agent tasks that need microVM isolation, with an open-source self-host path. The safe default for most agent builders: mature, open source, microVM-isolated and widely supported.
Compute platforms with sandboxes
General serverless or app platforms that also offer sandboxes, often with GPUs.
Fly Machines
Fly.io's low-level API for Firecracker VMs that start and stop in under a second and can be suspended to disk; the primitive underneath Fly.io's Sprites product.
- Firecracker microVM
- Pause/resume
How it differs: Teams that want raw, per-second-billed Firecracker VMs they orchestrate themselves rather than a sandbox SDK. A fast, well-priced Firecracker VM primitive for teams that want to assemble their own sandbox layer; for an agent-ready product on the same infrastructure look at Fly.io Sprites.
Cloud provider code execution
Managed code-execution tools from AWS, Azure, Google Cloud and OpenAI.
AWS Lambda MicroVMs
A Lambda resource type that runs a full Amazon Linux 2023 environment in a Firecracker microVM, restored from a pre-built snapshot, with suspend/resume and an HTTPS endpoint per VM.
- Firecracker microVM
- Pause/resume
How it differs: AWS-native agent sandboxes and interactive sessions that need VM isolation, an inbound endpoint and cheap idle time via suspend. The AWS-native way to get Firecracker-isolated, suspendable sandboxes with a per-VM endpoint, within an 8-hour lifetime and without a higher-level sandbox SDK.
Isolation primitives and runtimes
The hypervisors, user-space kernels, OS sandboxes and WebAssembly runtimes that sandbox platforms build on.
gVisor
Google's user-space application kernel for containers, with the runsc OCI runtime, GPU passthrough via nvproxy and checkpoint/restore; used by Modal, Beam, Anthropic, OpenAI and Google Cloud.
- User-space kernel
- Open source
- Self-hostable
- GPU
- Snapshots
How it differs: Sandboxing containers on hosts where you cannot or do not want to run a VM per workload, including GPU workloads. The most widely adopted non-VM sandbox boundary; choose it when a VM per workload is impractical or you need sandboxed GPUs.
Kata Containers
An OCI runtime that runs each Kubernetes pod in a lightweight VM with its own kernel, on QEMU, Cloud Hypervisor, Firecracker, Dragonball or StratoVirt.
- VM per pod
- Open source
- Self-hostable
- GPU
How it differs: Kubernetes clusters that need VM isolation per pod without leaving the container toolchain. The standard way to put a VM boundary around Kubernetes pods; choose it when your sandboxes are already pods.
libkrun
A dynamic library that lets any program launch a microVM in-process, on KVM in Linux or Hypervisor.framework on macOS; used by crun/Podman, krunkit and microsandbox.
- In-process microVM
- Open source
- Self-hostable
- GPU
How it differs: Embedding a microVM in your own tool on Linux or Apple Silicon without shipping a separate VMM. The microVM library to reach for when you want VM isolation inside your own tool, especially on macOS.
Firecracker vs alternatives
| Sandbox | Isolation | Open source | Self-host / BYOC | Cold start (vendor) | Max session | Snapshots / pause | GPU | SDKs |
|---|---|---|---|---|---|---|---|---|
| Firecracker | KVM microVM | Yes | Yes / No | <125 ms (spec) | Not documented | Yes / Yes | No | REST API, CLI |
| AWS Lambda MicroVMs | Firecracker microVM | No | No / No | sub-second to seconds (claimed) | 8 h | Yes / Yes | No | Python, JavaScript/TypeScript, PHP, CLI, REST API |
| E2B | Firecracker microVM | Yes | Yes / Yes | Not documented | 1 h / 24 h (Pro) | Yes / Yes | No | Python, JavaScript/TypeScript |
| Fly Machines | Firecracker microVM | No | No / No | <1 s start (claimed) | Not documented | Yes / Yes | Not documented | Go, CLI, REST API |
| gVisor | User-space kernel | Yes | Yes / No | ms (claim) | Not documented | Yes / Not documented | Yes | CLI |
| Kata Containers | VM per pod | Yes | Yes / No | Not documented | Not documented | Not documented / Not documented | Yes | CLI |
| libkrun | In-process microVM | Yes | Yes / No | Not documented | Not documented | Not documented / Not documented | Yes | Rust, C |
Frequently asked questions
What are the main alternatives to Firecracker?
Is there an open-source alternative to Firecracker?
Cite this page
Agent Sandboxes. (2026). Firecracker alternatives. agentsandboxes.org. Last reviewed November 9, 2026. https://agentsandboxes.org/alternatives/firecracker/
Found an error or a missing sandbox? Submit a correction — every entry links to the sources it relies on.