Azure Container Apps Sandboxes vs Unikraft Cloud

Both give each workload its own microVM with its own kernel. Azure bills per second inside your Azure account and scales to large fleets, while Unikraft Cloud wakes instances in milliseconds but caps self-serve plans at a small shared pool of running capacity.

The companies and products

Azure Container Apps Sandboxes

Azure Container Apps Sandboxes is a service inside Microsoft Azure that gives each agent or user an isolated microVM you create, suspend and resume through an SDK.

It is part of Azure Container Apps, the hyperscaler's serverless container platform, and lives in your Azure subscription as a sandbox group resource. Each sandbox boots from an OCI image or a snapshot, has its own kernel, and can be suspended with its memory and resumed in under a second. It is built for teams already on Azure that want stateful code execution with Azure networking, identity and billing.

Kind of product: A compute type inside Azure Container Apps, next to apps, jobs and dynamic sessions
Isolation: Each sandbox runs in its own secure boundary with its own kernel
Regions: 40 Azure regions, 9 of them in the EU
Sizes: Tiers from 0.25 cores / 0.5 GB to 4 cores / 8 GB; up to 16 vCPU / 32 GB by API
Quota: 500 concurrent active cores and 3,000 API requests a minute by default, raised by support request
Access: Microsoft Entra ID accounts only, with the Container Apps SandboxGroup Data Owner role
Compliance: Azure holds a SOC 2 Type 2 report for its cloud services; the scope list names which services it covers

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. “34th cheapest of 345” means 33 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	Azure Container Apps Sandboxes: 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 A software factory runs Docker, databases and test suites for hours; Azure needs the azure-dev image for Docker, Unikraft documents no container runtime inside, and boat ships both.	288th of 367, with limits $5,276 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 An assistant that lives on its machine all month needs room for many tools; Unikraft's Team pool is 8 GiB shared by every running instance, and Azure bills every running second.	302nd of 366, with limits $6,544 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 Short code runs that sleep between calls suit both; Azure fits this use case fully, while Unikraft's self-serve plans stop at 24 running instances.	34th cheapest of 345 $354 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 Azure fits hundreds of active user sandboxes on pay-as-you-go; Unikraft Pro holds 5,000 sleeping instances but only 24 running ones, so this needs Enterprise there.	22nd cheapest of 361 $2,260 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	153rd of 360, with limits $10,740 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	75th cheapest of 364 $1,728 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 that builds Docker images or runs Android emulators needs Docker and /dev/kvm; Azure documents no nested virtualization, Unikraft keeps it for Enterprise, and boat has both on every plan.	103rd cheapest of 377 $1,046 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 Unikraft's Team pool keeps one box running all month for $39, Azure costs $262 a month without a commitment, and boat costs $26 with SSH included.	322nd of 368, with limits $262 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 Computer-use agents need a screen to look at; Azure and Unikraft are both headless, while boat streams a Linux desktop at 60fps.	279th of 369, with limits $1,573 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 On Azure and Unikraft you install and run a headless browser in your own image; boat gives each sandbox Chromium on a desktop out of the box.	288th of 367, with limits $795 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	284th of 346, with limits $561 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	239th of 338, with limits $10,956 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	278th of 360, with limits $517 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	Azure Container Apps Sandboxes	Unikraft Cloud	boat
Isolation	MicroVM per sandbox with its own kernel	Minimal Linux microVM on a customized Firecracker VMM	Full VM with its own kernel on dedicated AMD Ryzen 9 9950X hosts
Machine size	Tiers up to 4 vCPU / 8 GB, and up to 16 vCPU / 32 GB by API, per sandbox	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
Docker and systemd inside	Depends on the image: azure-dev ships Docker on systemd; the default ubuntu image has only Buildah	The Dockerfile becomes the VM image; no container runtime inside is documented	Docker, systemd and root on every sandbox
Nested virtualization	Not documented	Yes, with a per-instance flag and permission, Enterprise only	Yes, /dev/kvm for Android emulators and VMs on every plan
Getting a shell	Interactive shell through the aca CLI, SDK or portal; no SSH	No SSH yet; commands and files go through the sandbox plugin and CLI	SSH into every sandbox, plus CLI and API exec
Desktop, browser and computer use	Headless; no desktop or managed browser	None built in; you can run your own headless browser from a Dockerfile	Linux desktop streamed at 60fps, Chromium and computer-use tools preinstalled
Sleep and wake	Suspends with memory and disk and resumes in under a second with processes running; traffic wakes it	Standby after a 1 second idle cooldown by default, with memory in stateful mode; traffic wakes it in milliseconds	Disk saved every minute and on stop; a stopped sandbox is started again by API
Fork and snapshots	Snapshot a running sandbox with its memory and create new sandboxes from it	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	Public HTTPS routes per published port; private endpoint from your VNet; no public IP	Services on its load balancer: HTTP on 80, HTTPS on 443, TLS-wrapped TCP on other ports; no public IP	HTTPS URLs for up to 50 ports, token-protected by default; raw TCP; dedicated IPv4 or IPv6
Outbound rules	Egress policy with allow, deny, rewrite and header rules by host, path and method; VNet integration	Network shield filters traffic, Enterprise only, limited access	Open internet, no provider-side allowlist
Keeping API keys out of the sandbox	Group secrets usable in egress header rules; Copilot and Anthropic tokens are injected into the sandbox at startup	Network shield can inject secrets into traffic, Enterprise only, limited access	Credentials proxy for model providers and any HTTPS API, on every plan; switch a credential to another account when credits run out
Coding agents	Copilot CLI and Claude Code images, run through the exec API	None preinstalled; you bring the agent in your own image	Seven agents preinstalled, driven from outside with a prompt, steer and events API
Scaling up a fleet	500 concurrent active cores by default; more by Azure support request	Up to 24 running instances on self-serve plans; more on Enterprise	Up to 2,000 sandboxes at once, self-serve
Regions	40 Azure regions, 9 of them in the EU	Dallas, Frankfurt, San Francisco, Singapore and Washington DC; more on request	EU only (Germany, Finland, France)

Every feature Battleships tracks (43)

Feature	Azure Container Apps Sandboxes	Unikraft Cloud	boat
Full VM (own kernel)	Yes	Yes	Yes
Docker inside	Yes	No	Yes
Nested virtualization	No	Yes	Yes
Root	Yes	Yes	Yes
Systemd	Yes	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	Yes	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	No	Not published	Yes
Public IPv4	No	No	No
Egress allowlist	Yes	Yes	No
Secret proxy	Yes	Yes	Yes
Secret proxy for any API	Yes	Yes	Yes
Preinstalled agents	Yes	No	Yes
Agent harness API	No	No	Yes
MCP server	No	No	No
GPU	No	Yes	No
Windows	No	No	No
Arm64	No	Yes	No
Self-hosting	No	Yes	No
BYOC	No	Yes	No
Open source	No	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	Yes	Yes	No
SSO	Yes	No	No
SOC 2	Yes	Yes	No
HIPAA	Yes	Yes	No
EU data residency	Yes	Yes	Yes
Zero data retention	Not published	Not published	Yes

Performance

Azure Container Apps SandboxesNot measured

Unikraft CloudNot measured

boat26.69 runs/s

There is no comparable CPU measurement for Azure Container Apps Sandboxes or Unikraft Cloud: neither is in the hpc-sandbox-benchmarks run that measured boat at 26.69 runs per second at 4 vCPU / 8 GB, on dedicated AMD Ryzen 9 9950X hosts. Unikraft states cold starts under 10 ms and Azure states resume in under a second; those are their own start-time figures, 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. Azure Container Apps Sandboxes 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	Azure Container Apps Sandboxes, 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	$68 · Pay-as-you-go	$39 · Hobby	$20 · $20/mo
One agent that never stops 4 vCPU / 8 GB, 50 GB disk, running 24/7 all month	$262 · Pay-as-you-go · with limits	$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	$3,421 · Pay-as-you-go	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	$989 · Pay-as-you-go	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	$2,148 · Pay-as-you-go	Can't run it	$2,000 · $2000/mo · with limits

Azure Container Apps Sandboxes: Azure bills per second on the Container Apps Consumption meters for the vCPU and memory of the sandbox's tier while it runs, including idle time before auto-suspend, which defaults to 5 minutes. There is no plan fee, stopped sandboxes pay no CPU or memory, and some regions such as West Europe charge more.

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: the Team pool has 8 vCPU and 8 GiB in total, so one 4 vCPU / 8 GB agent fills it, and the 50-agent, user-sandbox and burst scenarios fit no self-serve plan. Azure fits all three, but its default quota of 500 active cores caps a fleet until support raises it, and Docker inside means picking an image like azure-dev. Azure bills a running sandbox every second, so the always-on scenario only gets to $262 a month with a 3-year commitment. Unikraft also publishes no price for disk beyond its plan or for egress.

Scenario	Azure Container Apps Sandboxes	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	3-year commitment	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 Azure Container Apps Sandboxes when

your team is on Azure and needs hundreds of short stateful sandboxes that suspend with memory, follow strict egress rules, or run in many regions.

Memory suspend on every plan. For stateful jobs that sleep between requests: a sandbox suspends with its memory and resumes in under a second, processes still running.
Outbound rules without a contract. For agents that must stay on chosen hosts: egress rules by host, path and method come with pay-as-you-go, not only Enterprise.
Large fleets inside Azure. For teams on Azure: pay per second with Entra ID and VNets, in 40 regions, with room for hundreds of running sandboxes.

Use Unikraft Cloud when

you run a handful of small services or headless browsers that sleep most of the time and must wake in milliseconds, or want GPUs or on-prem under Enterprise.

Millisecond starts and scale-to-zero. For many small services that sleep most of the time: instances wake on the next request in milliseconds, and sleeping ones are free.
A small flat plan for one box. For one small always-on workload: the Hobby plan is free and the Team pool is a flat fee, with no per-second meter to watch.
GPUs, arm64 and your own hardware. For teams ready to sign Enterprise: NVIDIA GPUs, arm64 hosts, dedicated hosts, on-prem or your own cloud.

Where boat fits

Azure and Unikraft are both built around microVMs that sleep and wake fast. If what you are really running is agents that work for hours, a team comparing the two should look at boat: each agent gets a whole computer with Docker, /dev/kvm, SSH, a desktop and built-in coding agents, and fleets of full-size sandboxes need no sales call.

A whole machine to work in

Agents run docker compose, emulators and remote editors. Azure has Docker only on some images and no documented nested virtualization or SSH; Unikraft documents no Docker inside, has no SSH yet and keeps /dev/kvm for Enterprise.

A screen and a browser for every agent

Both Azure and Unikraft are headless, so a computer-use or browser agent needs you to build a browser, a virtual display and a streaming stack into your own image and keep it working. boat streams a 60fps desktop with Chromium.

Agents and keys built in

Azure injects Copilot and Anthropic tokens into the sandbox, where a prompt-injected agent can read them, and Unikraft's secret injection is Enterprise only. boat keeps keys in a proxy outside and drives seven preinstalled agents from outside.

Use boat when your agents need a real machine for hours of work: Docker, emulators, SSH, a desktop and a browser, coding agents driven from outside, and big fleets without a sales call. Compare it one to one: boat vs Azure Container Apps Sandboxes and boat vs Unikraft Cloud.

Questions people ask

Is Azure Container Apps Sandboxes cheaper than Unikraft Cloud?

For one agent, Unikraft is cheaper: one coding agent on workdays costs $68 a month on Azure and $39 on Unikraft's Team pool, and boat costs $20. For 50 agents in parallel, Azure costs $3,421 a month while no self-serve Unikraft plan is big enough, so the price is an Enterprise quote.

Which is faster, Azure Container Apps Sandboxes or Unikraft Cloud?

Neither has a comparable CPU measurement yet, so there is no speed claim either way. For starts, Unikraft states cold boots under 10 ms and Azure states resume from suspend in under a second; both are their own figures.

Can Azure Container Apps Sandboxes or Unikraft Cloud run Docker?

On Azure, the azure-dev image ships Docker on systemd, while the default ubuntu image has only Buildah. Unikraft builds your Dockerfile into the VM itself and does not document a container runtime inside. Every boat sandbox runs Docker and has /dev/kvm for emulators and VMs.

Can I SSH into Azure Container Apps Sandboxes or Unikraft Cloud?

No for both. Azure gives a shell through the aca CLI, SDK or portal, and Unikraft runs commands and moves files through its sandbox plugin and CLI. Every boat sandbox has an SSH endpoint.

Which one runs in more regions?

Azure, with 40 regions, 9 of them in the EU. Unikraft runs in Dallas, Frankfurt, San Francisco, Singapore and Washington DC, with more metros on request. boat runs in the EU 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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