smol machines vs Unikraft Cloud

Both run each workload in its own small Linux VM. smol machines bills the CPU and memory you actually use and lets you run the same open-source engine on your own servers, while Unikraft Cloud sells a flat pool of running capacity whose microVMs sleep when idle and wake in milliseconds.

The companies and products

smol machines

smol machines makes fast, isolated Linux microVMs that run the same way on your laptop, in their hosted cloud, or on your own servers.

The core is smolvm, an open-source microVM engine built on libkrun, where each machine has its own guest kernel. smol cloud is the paid hosted service that runs fleets of those machines behind a REST API and Node, Python and Rust SDKs. It is built for developers who want one VM model from local development to production, with live branching of running machines.

Isolation: Hardware-isolated microVM with its own guest kernel (libkrun)
Company: Founded 2026, Y Combinator Spring 2026, San Francisco, team of one listed
Open source: smolvm engine and smol SDK are open source and run on macOS, Linux and Windows hosts
Guests: Linux only; no Windows or macOS guests
Regions: No region field in the cloud create API
Uptime SLA: 99.95% on Pro, Startup and Enterprise

Unikraft Cloud

Unikraft Cloud is a microVM cloud from Unikraft Inc. that runs any Dockerfile-based workload as a minimal Linux microVM with millisecond cold starts and scale-to-zero.

Your Dockerfile becomes the VM image at build time, and each instance runs on a heavily customized Firecracker VMM, so it boots in milliseconds and can go into standby when no traffic arrives. It is a general compute platform built for dense, bursty work such as HTTP services, headless browsers and agent fleets, sold as flat self-serve plans plus Enterprise dedicated hosts, on-prem and bring your own cloud. It is not a dev machine you log into: instances are reached through services, the CLI and a sandbox plugin for commands and files.

Isolation: Linux microVM per instance on a customized Firecracker VMM; full VMs on Enterprise
Plans: Hobby free, Team $39/mo, Pro $199/mo, Enterprise custom; each caps running instances, vCPUs and memory
Running capacity: 2 / 8 / 24 running instances with 4 / 8 / 32 GiB memory in total on Hobby / Team / Pro
Regions: Dallas, Frankfurt, San Francisco, Singapore and Washington DC by default; more metros on request
Self-hosting: Dedicated host fleet, on-prem and BYOC on Enterprise
Compliance: SOC2, HIPAA and audit logs listed on Enterprise
Open source: The unikraft CLI is open source; the cloud platform is commercial

Which use cases each one fits

For each use case, Battleships prices every sandbox provider on the same workload and sorts them from the cheapest monthly bill up. “12th cheapest of 345” means 11 of the other 344 providers run that workload, with every feature it needs, for less. “With limits” means the provider runs it but misses something, so it is listed after every full match. Open a use case for its whole ranking and what each provider misses.

Use case and its workload	smol machines: price rank	Unikraft Cloud: price rank	boat: price rank
Software factory 100 at once · 4 vCPU / 8 GB · 2,200 sessions of 8 h a month smol machines runs Docker inside the VM and Unikraft documents no container runtime inside its instances; boat adds /dev/kvm, SSH and coding agents you drive from outside.	73rd of 367, with limits $604 a month	Can't run it	3rd cheapest of 367 $634 a month
Always-on AI employees 50 machines 24/7 · 2 vCPU / 4 GB	148th of 366, with limits $1,038 a month	Can't run it	5th cheapest of 366 $657 a month
Code interpreter bursts 100 at once · 1 vCPU / 2 GB · 200,000 sessions of 1 min a month smol machines fits short code runs well with a one-minute minimum and a /code endpoint, while Unikraft's self-serve pools hold at most 24 running instances.	12th cheapest of 345 $140 a month	Can't run it	186th of 345, with limits $2,000 a month
Sandboxes for your users 300 at once · 2 vCPU / 4 GB · 30,000 sessions of 23 min a month smol machines fits on its Startup plan; Unikraft's Pro pool holds 5,000 sleeping instances but only 24 running ones, so hundreds of active users need Enterprise.	7th cheapest of 361 $531 a month	Can't run it	Cheapest of 361 $209 a month
RL rollouts 1,000 at once · 2 vCPU / 4 GB · 1,000,000 sessions of 3 min a month smol machines can branch a running machine with its memory and processes, so many rollouts start from one prepared state.	111th of 360, with limits $6,978 a month	Can't run it	34th of 360, with limits $2,000 a month
Agent evals 250 at once · 4 vCPU / 8 GB · 15,000 sessions of 20 min a month	36th cheapest of 364 $670 a month	Can't run it	10th cheapest of 364 $200 a month
CI runners 40 at once · 8 vCPU / 16 GB · 6,000 sessions of 12 min a month CI jobs that build Docker images fit smol machines, but neither exposes nested virtualization on self-serve plans; boat has /dev/kvm on every plan.	66th cheapest of 377 $514 a month	Can't run it	4th cheapest of 377 $86 a month
24/7 dev boxes 1 machine 24/7 · 4 vCPU / 8 GB Both can keep a box all month, but neither has SSH, so you work through their command APIs; boat gives you SSH into every sandbox.	216th of 368, with limits $29 a month	219th of 368, with limits $39 a month	18th cheapest of 368 $26 a month
Computer-use agents 50 at once · 4 vCPU / 8 GB · 20,000 sessions of 15 min a month Neither has a hosted desktop, so you build your own inside the VM; boat streams a Linux desktop at 60fps with computer use built in.	90th of 369, with limits $156 a month	Can't run it	6th cheapest of 369 $200 a month
Browser-use agents 50 at once · 2 vCPU / 4 GB · 30,000 sessions of 10 min a month Both let you run your own headless Chromium inside a VM; boat ships Chromium on a desktop ready for agents.	176th of 367, with limits $136 a month	Can't run it	7th cheapest of 367 $200 a month
Scraping & bots (startup scale) 50 at once · 1 vCPU / 2 GB · 100,000 sessions of 3 min a month	241st of 346, with limits $242 a month	Can't run it	6th cheapest of 346 $90 a month
Mass scraping & bots (undetectable) 1,000 at once · 1 vCPU / 2 GB · 3,000,000 sessions of 2 min a month	148th of 338, with limits $4,344 a month	Can't run it	71st of 338, with limits $1,800 a month
Parallel red teaming 200 at once · 2 vCPU / 4 GB · 5,000 sessions of 30 min a month	252nd of 360, with limits $377 a month	Can't run it	2nd cheapest of 360 $200 a month
GPU eval jobs 10 at once · 8 vCPU / 32 GB · 500 sessions of 30 min a month	Can't run it	Can't run it	Can't run it
macOS agents 5 at once · 4 vCPU / 8 GB · 1,000 sessions of 20 min a month	Can't run it	Can't run it	Can't run it

Key features

Feature	smol machines	Unikraft Cloud	boat
Isolation	libkrun microVM with its own guest kernel	Minimal Linux microVM on a customized Firecracker VMM	Full VM with its own kernel on dedicated AMD Ryzen 9 9950X hosts
Machine size	Up to 8 vCPU / 16 GB on Standard, 16 vCPU / 24 GB on Pro, 32 vCPU / 32 GB on Startup	A plan pool shared by all running instances: 2 vCPU / 4 GiB, 8 vCPU / 8 GiB or 24 vCPU / 32 GiB	4 vCPU / 8 GB by default, up to 16 vCPU / 32 GB per sandbox on the $100 plan and above
Running at once	20 on Standard, 100 on Pro, 1,000 on Startup; stopped machines still hold a slot	2, 8 or 24 running instances on self-serve plans; more needs Enterprise	100 to 2,000 sandboxes at once on paid plans, no session cap
Docker inside	Yes, with Docker data on the machine's ext4 disk	The Dockerfile becomes the VM image; no container runtime inside documented	Yes, Docker, systemd and root, like any Ubuntu machine
Nested virtualization	Not exposed in the cloud API; a local smolvm flag only	Per-instance flag, Enterprise only	Yes, /dev/kvm for Android emulators and VMs on every plan
Shell access	Command API and a WebSocket terminal capped at one hour per connection; no SSH	Sandbox plugin and CLI for commands and files; no SSH yet	SSH, plus a command API and terminal
Sleep and wake	A command or terminal starts a stopped machine; idle apps wake on the next request	Standby after a 1 second idle cooldown; traffic wakes it in milliseconds, with memory kept in stateful mode	Disk saved every minute and on stop; a stopped sandbox costs nothing and is started by API
Fork and checkpoints	Branch a running machine with its memory and processes; checkpoints capture RAM to a file	Checkpoint memory and volumes of a running microVM, then start new instances from it; forking is in preview	Fork a running sandbox with its disk; snapshots every minute
Inbound access	Up to 16 published ports through a returned URL; no dedicated IP	Load balancer services: HTTP on 80, HTTPS on 443, TLS-wrapped TCP on other ports; no public IP per instance	HTTPS URLs for up to 50 ports, token-protected by default; raw TCP; dedicated IPv4 or IPv6
Outbound rules	Blocked, open, or an allowlist of hosts and CIDR ranges	Network shield filters traffic, Enterprise only, limited access	Open internet, no provider-side allowlist
Keeping API keys out of the sandbox	Cloud secrets are environment variables the guest can read	Network shield can inject secrets into traffic, Enterprise only	Credentials proxy for model providers and any HTTPS API on every plan; switch a credential to another account when credits run out
Desktop, browser and coding agents	No hosted desktop; registry images with the Codex CLI and Harbor	None built in; you bring your own browser and agent in the image	Linux desktop at 60fps, Chromium, computer use, and seven coding agents with a prompt, steer and events API
Regions	No region choice in the cloud API	Dallas, Frankfurt, San Francisco, Singapore and Washington DC, more on request	EU only (Germany, Finland, France), with EU data residency
Self-hosting	Open-source smolvm runs on your laptop or your own servers	Dedicated hosts, on-prem or your own cloud on Enterprise	No

Every feature Battleships tracks (43)

Feature	smol machines	Unikraft Cloud	boat
Full VM (own kernel)	Yes	Yes	Yes
Docker inside	Yes	No	Yes
Nested virtualization	No	Yes	Yes
Root	Not published	Yes	Yes
Systemd	Not published	Not published	Yes
Desktop GUI	No	No	Yes
Browser	No	No	Yes
Computer-use API	No	No	Yes
SSH	No	No	Yes
Persistent disk	Yes	Yes	Yes
Pause/resume	Yes	Yes	Yes
Automatic snapshots	No	Yes	Yes
Fork/clone	Yes	Yes	Yes
Live fork (no pause)	Yes	Yes	Yes
Memory fork	Yes	Yes	No
Custom image (Docker or snapshot)	Yes	Yes	Yes
≥24 h sessions	Yes	Yes	Yes
Idle auto-stop	Yes	Yes	No
Wake on request	Yes	Yes	No
HTTPS preview URLs	Yes	Yes	Yes
Raw TCP inbound	Not published	Not published	Yes
Public IPv4	No	No	No
Egress allowlist	Yes	Yes	No
Secret proxy	No	Yes	Yes
Secret proxy for any API	No	Yes	Yes
Preinstalled agents	Yes	No	Yes
Agent harness API	No	No	Yes
MCP server	Yes	No	No
GPU	No	Yes	No
Windows	No	No	No
Arm64	Yes	Yes	No
Self-hosting	Yes	Yes	No
BYOC	Yes	Yes	No
Open source	Yes	No	No
Scoped API keys	Not published	Not published	Yes
Spend limits	Yes	Not published	Yes
Usage per sandbox (API)	Yes	No	Yes
Audit logs	Not published	Yes	No
SSO	Yes	No	No
SOC 2	No	Yes	No
HIPAA	No	Yes	No
EU data residency	No	Yes	Yes
Zero data retention	Not published	Not published	Yes

Performance

smol machinesNot measured

Unikraft CloudNot measured

boat26.69 runs/s

There is no comparable CPU measurement for smol machines or Unikraft Cloud: neither has been run on the StarSling hpc-sandbox-benchmarks test. boat did 26.69 runs per second on that Node.js build-and-test loop at 4 vCPU / 8 GB. smol publishes a boot under 200ms and Unikraft cold starts under 10 ms, which are start times, not CPU speed.

Node.js build-and-test loop at 4 vCPU / 8 GB, higher is better. Measured with the open hpc-sandbox-benchmarks suite. smol machines and Unikraft Cloud have no published run in this suite yet, so there is no like-for-like number to compare.

Pricing in five scenarios

Each bill is priced from the providers' public price lists by the open Battleships engine, with the cheapest plan that runs the scenario.

Scenario	smol machines, a month	Unikraft Cloud, a month	boat, a month
One coding agent, workdays 4 vCPU / 8 GB, 50 GB disk, 8 hours a day, 22 days a month, files kept between days	$25 · Standard	$39 · Hobby	$20 · $20/mo
One agent that never stops 4 vCPU / 8 GB, 50 GB disk, running 24/7 all month	$93 · Standard	$39 · Hobby	$26 · $20/mo
50 agents in parallel 50 machines of 4 vCPU / 8 GB at once, 8-hour sessions, 1,100 sessions a month, Docker inside	$1,139 · Pro	Can't run it	$317 · $20/mo × 3 seats
Sandboxes for your users 2 vCPU / 4 GB, 30,000 sessions of 10 minutes a month, up to 300 at once	$465 · Startup	Can't run it	$200 · $100/mo × 2 seats
1,000 short jobs at once 2 vCPU / 4 GB, 1,000 at once, 3 minutes each, 200,000 jobs a month	$1,389 · Startup	Can't run it	$2,000 · $2000/mo · with limits

smol machines: smol cloud charges a base fee for every hour a machine runs plus the CPU and memory the guest uses, with a one-minute minimum and disk billed while stopped. Pro and Startup are monthly fees on top of usage, not credit.

Unikraft Cloud: Unikraft charges a flat monthly fee for a pool of running capacity: free for 2 vCPU / 4 GiB, $39 for 8 vCPU / 8 GiB, $199 for 24 vCPU / 32 GiB, with sleeping instances not counted. It publishes no per-hour or egress rate, so anything bigger is an Enterprise quote.

Unikraft Cloud: Plans start at $20 a month, and the whole fee is usage credit. You pay per second while a sandbox runs, and a stopped sandbox costs nothing and keeps its disk.

Limits in those scenarios

Unikraft's limits are pools every running instance shares: one 4 vCPU / 8 GB agent fills the Team pool, so 50 agents, sandboxes for your users and 1,000 short jobs at once fit no self-serve plan. smol machines fits all five scenarios, but 50 agents need Pro and 1,000 jobs at once need Startup, whose fees sit on top of usage. boat fits four, and at 1,000 short jobs at once its $2,000 plan queues starts above 90 a minute.

Scenario	smol machines	Unikraft Cloud	boat
One coding agent, workdays	None that bite	flat pool: the tier is billed whether used or not disk beyond 0 GiB: price unknown egress price not published	None that bite
One agent that never stops	None that bite	flat pool: the tier is billed whether used or not disk beyond 0 GiB: price unknown egress price not published	None that bite
50 agents in parallel	None that bite	no pool tier with 200 vCPU / 400 GiB for 50 VMs no published per-resource rate	None that bite
Sandboxes for your users	None that bite	no pool tier with 600 vCPU / 1,200 GiB for 300 VMs no published per-resource rate	None that bite
1,000 short jobs at once	None that bite	no pool tier with 2,000 vCPU / 4,000 GiB for 1,000 VMs no published per-resource rate	max 2,400 starts/day (needs ~6,667) max 600 starts/hour (needs ~1,000) bursts above 90 starts/min are queued (a burst of 333 takes ~4 min to start)

Which one should you use?

Use smol machines when

you want one open-source VM engine from your laptop to your own servers, pay only for what guests use, or branch running machines with their memory.

Open source, from laptop to your servers. Teams that want one VM engine locally, in a hosted cloud and on their own servers get it with open-source smolvm.
Pay for what the guest uses. smol bills the CPU and memory a machine actually uses, and self-serve plans scale to 1,000 machines and 32 vCPU each.
Live branches and outbound allowlists. Useful for RL and locked-down agents: branch a running machine with its memory, and allow only listed hosts on any plan.

Use Unikraft Cloud when

you run small services or headless browsers that sleep most of the time and must wake in milliseconds, or need US and Asia regions.

Millisecond wake from standby. Best for many small services that sleep most of the time and must answer the next request in milliseconds.
A flat fee for an always-on box. One small service running all month fits a fixed Team pool fee, with no usage meter to watch.
Regions in the US and Asia. Unikraft runs in Dallas, San Francisco, Washington DC and Singapore as well as Frankfurt, with more metros on request.

Where boat fits

smol machines and Unikraft Cloud are both built around small, fast microVMs you reach through an API. If what you are running is coding agents that need a whole machine, with Docker, emulators, SSH, a desktop and keys kept out of reach, boat gives each one that machine on every plan.

A whole machine with /dev/kvm and SSH

Neither has SSH, smol cloud does not expose nested virtualization, and Unikraft keeps it for Enterprise. An agent that runs an Android emulator or a VM has no way to start one on either self-serve plan.

Keys that never enter the sandbox

smol cloud secrets are environment variables the guest can read, and Unikraft's secret injection is Enterprise only. So one prompt injection can leak real keys; boat's credentials proxy keeps them outside for any HTTPS API.

A desktop and agents ready to drive

Neither ships a desktop or a computer-use stack, so you build and maintain your own. boat streams a 60fps Linux desktop with Chromium and lets you drive seven preinstalled coding agents inside from outside.

Use boat when your agents need a whole machine to work in: Docker, emulators, SSH, a desktop and a browser, coding agents you drive from outside, and keys that never enter the sandbox. Compare it one to one: boat vs smol machines and boat vs Unikraft Cloud.

Questions people ask

Is smol machines cheaper than Unikraft Cloud?

For one coding agent on workdays, smol machines is $25 a month against $39 for Unikraft's Team pool. For one agent that never stops, Unikraft's flat $39 a month beats smol's $93 a month. For 50 agents, user sandboxes or 1,000 short jobs, only smol machines has a self-serve price.

Which is faster?

Neither has a CPU score on the benchmark used here, so there is no fair speed comparison. On start time, Unikraft claims cold starts under 10 ms and smol claims boots under 200ms; both are vendor figures.

Can smol machines or Unikraft Cloud run Docker?

smol machines runs Docker inside the VM, with Docker data on the machine's ext4 disk. Unikraft builds your Dockerfile into the VM image and documents no container runtime inside a running instance. boat runs Docker, systemd and /dev/kvm in every sandbox.

Can I SSH into smol machines or Unikraft Cloud?

Not today. smol cloud gives you a command API and a WebSocket terminal, and Unikraft gives you a sandbox plugin and CLI. boat gives you SSH into every sandbox.

Can I self-host either one?

smolvm, the engine behind smol machines, is open source and runs on your laptop or servers. Unikraft offers dedicated hosts, on-prem and your own cloud on Enterprise, and its CLI is open source. boat is a hosted service only.

Is boat SOC 2 compliant?

SOC 2 is in progress. We're open about where we stand: live status at status.ascii.dev and our data retention policy at docs.boat.dev/data-retention.

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