Mitos vs Modal
Mitos gives each agent its own kernel and forks a running one into a fleet. Modal runs agent code on gVisor with snapshots, and is closed source.
Mitos is the open, microVM-isolated primitive: an own kernel per agent and a live fork of running memory. Modal isolates with gVisor, offers snapshot and restore rather than a live fork, and is a closed runtime. For running and forking many agents safely and openly, Mitos is built for it.
Mitos vs Modal, capability by capability
Capabilities from each project's public docs as of June 2026, not a head-to-head benchmark. Numbers move; the source of truth is each project's own repo and docs.
| Capability | Mitos | Modal |
|---|---|---|
| Fork a running VM (memory + processes) | ✓ memory + processes | ✗ snapshot |
| Isolation model | ✓ Firecracker microVM, KVM | ✗ gVisor |
| Published marginal cost per fork | ✓ ~3 MiB / fork | ✗ |
| Open source | ✓ Apache 2.0 | ✗ closed |
| Native GPU in sandboxes | ◐ GPU-second metered | ✓ first-class |
| Fully managed cloud | ✓ yes | ✓ |
What sets Mitos apart
Own kernel vs shared kernel
Mitos runs each agent in a Firecracker microVM with its own kernel under KVM. Modal isolates with gVisor, a userspace kernel that shares the host kernel surface. For untrusted, model-written code, an own-kernel boundary is the stronger default.
A live fork, not a snapshot
Mitos copies a running machine’s memory and processes into many daughters at once, so they resume warm and share pages copy-on-write. Modal offers snapshot and restore, which is not the same as branching one running machine into a fleet.
Open, so you are never trapped
The Mitos engine is Apache 2.0, the same code the managed service runs, so you can read it, self-host it, and verify it yourself. Modal is a closed runtime, so the only place to run your workloads is on Modal’s cloud.
Why teams pick Mitos over Modal
- Own-kernel microVM isolation (Firecracker + KVM), a stronger default than gVisor for untrusted code.
- A live fork of running memory into a fleet, not snapshot and restore.
- An Apache-2.0 engine you can run yourself; Modal is closed.
Mitos vs Modal, in brief
Does Modal use microVMs?
Modal isolates with gVisor, a userspace kernel, not a microVM with its own kernel. Mitos runs every fork as a Firecracker microVM under KVM, the stronger default for untrusted code.
Can Modal fork a running sandbox?
Modal offers snapshot and restore, not a live fork of running memory into many daughters. That live fork is what Mitos is built around.
Is Modal open source?
No, Modal is closed. The Mitos engine is Apache 2.0, so you can self-host and you are never locked in.