Docker Cloud Sandboxes vs smol machines

Both give each agent its own microVM with its own Linux kernel. Docker Cloud Sandboxes is your local sbx sandbox moved to the cloud, for up to 24 hours and 10 at a time, while smol machines has no session cap, runs up to 1,000 machines and is open source end to end.

The companies and products

Docker Cloud Sandboxes

Docker Cloud Sandboxes runs Docker's sbx coding-agent microVMs on Docker-managed compute instead of your laptop.

Each sandbox is a microVM with its own Linux kernel and its own Docker Engine, started from the same sbx CLI you use locally, with Claude Code, Codex and other agents ready to run. You can move a sandbox from your laptop to the cloud and back, publish HTTPS ports and SSH in. It launched on September 24, 2026, is billed pay-as-you-go on a personal Docker account, and is built for developers who want their local agent sandboxes to keep going off their machine.

Isolation: MicroVM per sandbox with its own Linux kernel and its own Docker Engine
Launched: September 24, 2026
Machine sizes: 1 vCPU / 2 GiB up to 16 vCPU / 32 GiB, CPU only, amd64 or arm64 by account
Session length: 1 hour by default, extendable to 24 hours from creation
Default quota: 10 concurrent and 50 stored sandboxes per account
Account: Pay-as-you-go plan on a personal Docker account, even inside an organization
Regions: Not published

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

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. “280th cheapest of 367” means 279 of the other 366 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	Docker Cloud Sandboxes: price rank	smol machines: price rank	boat: price rank
Software factory 100 at once · 4 vCPU / 8 GB · 2,200 sessions of 8 h a month A software factory runs many agents for days; Docker stops each sandbox at 24 hours and allows 10 at once, smol has no cap, and boat adds /dev/kvm and an API to drive agents.	280th of 367, with limits $4,928 a month	73rd of 367, with limits $604 a month	3rd cheapest of 367 $634 a month
Always-on AI employees 50 machines 24/7 · 2 vCPU / 4 GB An assistant that lives on its machine all month does not fit in one Docker session; smol can keep a machine running, but with no desktop, browser or key proxy.	276th of 366, with limits $5,110 a month	148th of 366, with limits $1,038 a month	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 best of the three, with a one-minute minimum and branches of a warm machine that pay that minimum once.	119th of 345, with limits $233 a month	12th cheapest of 345 $140 a month	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 Serving your own users needs more than Docker's default 10 sandboxes at once; smol fits on its Startup plan, and boat adds a desktop, hosting on 50 ports and a credentials proxy.	136th of 361, with limits $1,628 a month	7th cheapest of 361 $531 a month	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 Both Docker and smol can start many rollouts from one prepared state with its memory, but Docker's 10-at-once default holds the fan-out back.	114th of 360, with limits $7,000 a month	111th of 360, with limits $6,978 a month	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 Evals run many sandboxes side by side, which smol handles on its paid plans and Docker's default of 10 at once does not.	167th of 364, with limits $1,400 a month	36th cheapest of 364 $670 a month	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 that builds Android apps or boots VMs needs /dev/kvm, which boat exposes and neither Docker nor smol cloud offers.	172nd of 377, with limits $672 a month	66th cheapest of 377 $514 a month	4th cheapest of 377 $86 a month
24/7 dev boxes 1 machine 24/7 · 4 vCPU / 8 GB	127th of 368, with limits $204 a month	216th of 368, with limits $29 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 Computer-use agents need a screen; Docker's sandboxes are terminal only, smol leaves the desktop to you, and boat streams a 60fps Linux desktop.	268th of 369, with limits $1,400 a month	90th of 369, with limits $156 a month	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	277th of 367, with limits $700 a month	176th of 367, with limits $136 a month	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	262nd of 346, with limits $350 a month	241st of 346, with limits $242 a month	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	190th of 338, with limits $7,000 a month	148th of 338, with limits $4,344 a month	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	248th of 360, with limits $350 a month	252nd of 360, with limits $377 a month	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	Docker Cloud Sandboxes	smol machines	boat
Isolation	MicroVM with its own Linux kernel and its own Docker Engine; hypervisor not named	libkrun microVM with its own guest kernel	Full VM with its own kernel on dedicated AMD Ryzen 9 9950X hosts
Session length	1 hour by default, at most 24 hours from creation; resuming starts a new timer	No provider cap; an optional lifetime you set	No cap on paid plans; you set the time to live
Sandboxes at once	10 by default; no published way to raise it	20 on Standard, 100 on Pro, 1,000 on Startup; stopped machines still hold a slot	100 on the $20 plan, up to 2,000 on higher plans, self-serve
Stop and resume	Stop keeps memory and files; a stopped sandbox costs nothing	Files survive a stop, memory paths are emptied; stopped disk keeps billing; a stopped machine wakes on the next command	Disk saved every minute and on stop; a stopped sandbox costs nothing; resume boots the machine again
Fork	Snapshot a running sandbox with disk or disk and memory, then restore it as a new sandbox	Branch a running machine into children that keep its memory and processes	Fork a running sandbox with its disk
Docker inside	Yes, its own Docker Engine; agent runs as a non-root user with sudo	Yes, with Docker data on the machine's ext4 disk	Yes, with root and systemd
Nested virtualization	Not documented	Not exposed in the cloud API; a local smolvm flag only	Yes, /dev/kvm for Android emulators and VMs
Shell access	SSH with Docker-issued certificates, plus the sbx CLI	Command API, sessions and a WebSocket terminal capped at one hour per connection; no SSH	SSH, plus a command API and terminal
Inbound access	Public HTTPS URL per published port, not protected by Docker sign-in; not a TCP tunnel	Up to 16 published ports through a returned URL or an authenticated connect route; no dedicated IP	HTTPS URLs for up to 50 ports, token-protected by default; raw TCP; dedicated IPv4 or IPv6
Outbound rules	Allow and deny rules by host, with allow-all, balanced and deny-all presets	Blocked, open, or an allowlist of hosts and CIDR ranges	Open internet, no provider-side allowlist
Desktop and browser	Terminal sessions only	No hosted desktop; a guide shows running your own Chromium inside a machine	60fps Linux desktop with Chromium and computer use
Coding agents	Claude Code, Codex, Copilot, OpenCode and more, run and attached to from the sbx CLI	Registry images with the Codex CLI and the Harbor eval harness, run through the command API	Seven agents preinstalled, with a prompt, steer and events API to drive them from outside
Keeping API keys out of the sandbox	Cloud proxy sets the auth header for built-in AI services and custom hosts; the sandbox sees a placeholder	Cloud secrets are environment variables the guest can read; placeholder swapping only in self-hosted smolvm	Credentials proxy for model providers and any HTTPS API; switch a credential to another account when credits run out
Running it yourself	Same microVM and CLI on your laptop; move a sandbox between laptop and cloud	Open-source smolvm runs on your laptop or your own servers, with the same .smolmachine artifact	Cloud only, in the EU (Germany, Finland, France)

Every feature Battleships tracks (43)

Feature	Docker Cloud Sandboxes	smol machines	boat
Full VM (own kernel)	Yes	Yes	Yes
Docker inside	Yes	Yes	Yes
Nested virtualization	No	No	Yes
Root	Yes	Not published	Yes
Systemd	Not published	Not published	Yes
Desktop GUI	No	No	Yes
Browser	No	No	Yes
Computer-use API	No	No	Yes
SSH	Yes	No	Yes
Persistent disk	Yes	Yes	Yes
Pause/resume	Yes	Yes	Yes
Automatic snapshots	Yes	No	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	No	Yes	No
Wake on request	Not published	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	Yes	No	Yes
Secret proxy for any API	Yes	No	Yes
Preinstalled agents	Yes	Yes	Yes
Agent harness API	No	No	Yes
MCP server	Yes	Yes	No
GPU	No	No	No
Windows	No	No	No
Arm64	Yes	Yes	No
Self-hosting	No	Yes	No
BYOC	No	Yes	No
Open source	No	Yes	No
Scoped API keys	Not published	Not published	Yes
Spend limits	Not published	Yes	Yes
Usage per sandbox (API)	No	Yes	Yes
Audit logs	Not published	Not published	No
SSO	Yes	Yes	No
SOC 2	No	No	No
HIPAA	No	No	No
EU data residency	No	No	Yes
Zero data retention	Not published	Not published	Yes

Performance

Docker Cloud SandboxesNot measured

smol machinesNot measured

boat26.69 runs/s

There is no comparable CPU measurement for either one: neither Docker Cloud Sandboxes nor smol cloud has been run on the StarSling hpc-sandbox-benchmarks test, and Docker does not say what hardware it uses. boat did 26.69 runs per second on that Node.js build-and-test loop at 4 vCPU / 8 GB, on dedicated AMD Ryzen 9 9950X hosts. smol publishes a boot time under 200ms for smolvm, which is a start-time figure, 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. Docker Cloud Sandboxes and smol machines 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	Docker Cloud Sandboxes, a month	smol machines, 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	$49 · Docker Agentic Platform (pay-as-you-go)	$25 · Standard	$20 · $20/mo
One agent that never stops 4 vCPU / 8 GB, 50 GB disk, running 24/7 all month	$204 · Docker Agentic Platform (pay-as-you-go) · with limits	$93 · Standard	$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	$2,464 · Docker Agentic Platform (pay-as-you-go) · with limits	$1,139 · Pro	$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	$700 · Docker Agentic Platform (pay-as-you-go) · with limits	$465 · Startup	$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	$1,400 · Docker Agentic Platform (pay-as-you-go) · with limits	$1,389 · Startup	$2,000 · $2000/mo · with limits

Docker Cloud Sandboxes: Docker bills per second for the size you pick, from $0.07 an hour for 1 vCPU / 2 GiB to $1.12 an hour for 16 vCPU / 32 GiB, with no monthly fee. A stopped sandbox costs nothing, and volumes and egress are free.

smol machines: smol cloud charges a base fee for every hour a machine runs, plus the CPU and memory the guest actually uses, with a one-minute minimum and disk billed even while stopped. Pro ($20 a month) and Startup ($150 a month) are fees on top of usage, not credit.

smol machines: 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

Docker ends every sandbox 24 hours after creation, so one agent that never stops does not fit in a single session, and its default of 10 sandboxes at once rules it out for 50 agents in parallel, sandboxes for your users and 1,000 short jobs at once. smol machines fits all five scenarios, but 50 agents need Pro and 1,000 short jobs need Startup, and stopped machines still count toward those caps. boat has no session cap, but at 1,000 short jobs at once its plans queue starts above 90 a minute, while smol on Startup starts the whole burst.

Scenario	Docker Cloud Sandboxes	smol machines	boat
One coding agent, workdays	None that bite	None that bite	None that bite
One agent that never stops	Docker Agentic Platform (pay-as-you-go): sessions capped at 24 h	None that bite	None that bite
50 agents in parallel	Docker Agentic Platform (pay-as-you-go): max 10 concurrent	None that bite	None that bite
Sandboxes for your users	Docker Agentic Platform (pay-as-you-go): max 10 concurrent	None that bite	None that bite
1,000 short jobs at once	Docker Agentic Platform (pay-as-you-go): max 10 concurrent	None that bite	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 Docker Cloud Sandboxes when

you already run agents in sbx on your laptop and want a few to keep going in the cloud for up to a day, with memory kept across stops and keys kept out of the VM.

Stop with memory kept. For agents that pause between steps: a stopped Docker sandbox comes back with its memory and running processes, and costs nothing while stopped.
Keys stay outside the VM. Docker's cloud proxy adds the auth header for you, so the sandbox only sees a placeholder, while smol cloud passes secrets in plainly.
Your laptop sandbox, in the cloud. If you already run sbx locally, the cloud is the same microVM and CLI, and you can move a sandbox either way.

Use smol machines when

you need machines that run as long as you like or by the hundred, live branches with memory, or one open-source VM engine you can also run on your own servers.

No session cap, many at once. For long or wide jobs: a smol machine runs until you stop it, and the Startup plan holds up to 1,000 machines.
Live branches that wake on demand. For RL and test fan-out: branch a running machine with its memory and processes, and wake stopped ones on the next command.
Open source, on your own servers. Teams that want one VM engine from laptop to their own servers can run smolvm themselves, with the same packed machine.

Where boat fits

Docker and smol both give an agent a small VM boundary, and leave the rest of the machine to you. If your agents run for days or by the dozen, need emulators, a desktop or a browser, or must be driven from your own app, look at boat.

Runs as long and as wide as the work

Docker ends each sandbox 24 hours after creation and runs 10 at once, so your code must stop and resume agents. smol has no cap, but 50 agents need its Pro plan, a fee on top of usage. boat's $20 plan runs 100.

A whole machine, screen included

Neither Docker nor smol cloud offers /dev/kvm or a desktop, so Android emulators cannot start there and computer-use agents have no screen. On smol you build and maintain your own browser stack. boat streams a 60fps desktop with Chromium.

Drive agents inside from outside

On Docker you attach to an agent's terminal from the sbx CLI; on smol you run it through exec calls. Either way you write a wrapper and parse text to know when it is done. boat has a prompt, steer and events API.

Use boat when your agents run for days or by the dozen and need a whole machine: Docker, Android emulators, SSH, a desktop and a browser, with coding agents you drive from outside and keys that never enter the sandbox. Compare it one to one: boat vs Docker Cloud Sandboxes and boat vs smol machines.

Questions people ask

Is Docker Cloud Sandboxes cheaper than smol machines?

Not in these scenarios. For one coding agent on workdays at 4 vCPU / 8 GiB, it is $49 on Docker against $25 on smol machines, and $20 on boat. In the other four scenarios Docker does not fit, because of its 24-hour session cap or its default of 10 sandboxes at once.

Which is faster, Docker Cloud Sandboxes or smol machines?

Neither has a comparable CPU measurement yet, so there is no fair speed answer. boat did 26.69 runs per second on the hpc-sandbox-benchmarks Node.js test at 4 vCPU / 8 GB.

Can Docker Cloud Sandboxes and smol machines run Docker?

Yes, both run Docker inside the VM. Docker gives each sandbox its own Docker Engine, and smol's guide says Docker data must live on the machine's ext4 disk. Neither offers /dev/kvm in the cloud for Android emulators or nested VMs, which boat does.

Can either run longer than 24 hours?

smol machines can: it has no provider cap, only an optional lifetime you set. A Docker cloud sandbox expires after one hour by default and cannot be extended past 24 hours from creation. boat has no session cap on paid plans.

Which one can fork a running sandbox with its memory?

Both. Docker snapshots a running sandbox with its memory and restores it as a new one, and smol branches a running machine into children that keep its memory and processes. boat forks a running sandbox with its disk, and the fork boots fresh.

Can I run them on my own machine?

Docker Sandboxes run on your laptop with the same sbx CLI, and you can move a sandbox to the cloud and back. smol's engine, smolvm, is open source and runs on your laptop or your own servers. boat is a hosted service only.

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