It needs a Linux host with KVM.

One command checks the host before you create anything. It reports package and daemon versions, KVM, host tools, Firecracker, the guest kernel, profiles, limits and free capacity, and says how to fix what fails.

Host
Linux with KVM
Linux guests
Firecracker, with a guest kernel
Windows guests
libvirt and QEMU, with OVMF and swtpm
Also on the host
Docker, iproute2 and iptables
Packages
A Debian package that bundles Firecracker and a guest kernel, and NixOS modules
CLI
Linux and macOS, on amd64 and arm64
kiln host doctor kiln login --api-url http://localhost:8080 --token <token>

Three ways to reach the API.

Loopback HTTP
The default. kilnd listens on 127.0.0.1:8080, and only the host itself can reach it.
Remote HTTPS
Kiln gets a Let's Encrypt certificate for your domain. The domain has to resolve to the host, with ports 80 and 443 open.
Remote HTTP
Off unless the host and the client both opt in. A VPN or tailnet does not remove either opt‑in.

To serve the API over HTTPS, set three variables on the host and log in with the domain.

KILN_TLS_ENABLED=true
KILN_TLS_DOMAIN=kiln.example.com
KILN_ACME_EMAIL=operator@example.com

Every request carries a bearer token, whichever way it arrives.

Keep the disk in check.

Root filesystems are sparse files, so a 64G disk takes only the space the guest has written. Cached images and old machine directories are what build up.

Cleanup never touches Docker images, or anything a machine or image still uses.

  • kiln disk usage

    Shows what images, machines and caches take up.

  • kiln cleanup --dry-run

    Lists what a cleanup would delete, and deletes nothing.

  • kiln cleanup

    Deletes image and machine directories nothing refers to, superseded profile caches and temporary files older than an hour.

Watch the host.

Four commands report on the node and its machines. They are live snapshots, and Kiln keeps no history.

kiln node healthkiln node capacitykiln metrics summarykiln vm metrics dev

Kiln is not released yet.

It is in private development, and there is nothing to download today.

Kiln Console, the iOS companion app, is at its first milestone. It is a read-only dashboard running on sample data.