Vercel Sandbox vs Unikraft Cloud
Both run each sandbox in a Firecracker microVM. Vercel Sandbox bills each run as it goes and stops every session after 24 hours, while Unikraft Cloud sells a flat pool of running capacity whose microVMs sleep when idle and wake in milliseconds.
The companies and products
Vercel Sandbox
Vercel is a cloud platform for web apps and agents, and Vercel Sandbox is its product for running untrusted or agent-written code in isolated Linux microVMs.
Each sandbox is a Firecracker microVM with its own kernel, started from a Vercel image, your own OCI image, or a saved snapshot. You drive it with the JavaScript or Python SDK or the sandbox CLI: run commands, move files, open ports, and set network rules. It is aimed at code interpreters, app builders, test runs and agent tools, and Vercel's docs say it is not meant to run nonstop.
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.
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. “22nd cheapest of 345” means 21 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 | Vercel Sandbox: 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 Neither has a desktop to check the UI an agent built, Vercel stops at 24 hours, and Unikraft documents no Docker inside an instance; boat has both. | 244th of 367, with limits $3,351 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 Vercel's docs say sandboxes are not meant to run nonstop, and Unikraft's Team pool is 8 GiB of memory for every running instance together. | 257th of 366, with limits $3,657 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 bursts suit both designs, but only Vercel Sandbox has a published rate for them; Unikraft's self-serve plans cap you at 24 running instances. | 22nd cheapest of 345 $216 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 Vercel fits hundreds of sandboxes for your users on Pro; Unikraft's biggest self-serve pool holds 24 running instances, so this needs an Enterprise quote there, and boat ranks first. | 15th cheapest of 361 $1,267 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 Many short parallel rollouts suit Vercel's high concurrency; Unikraft has no self-serve pool big enough to run them at once. | 3rd cheapest of 360 $15,761 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 | 69th cheapest of 364 $1,508 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 Vercel, which allows Docker with sudo; Unikraft documents no container runtime inside, and boat adds /dev/kvm for emulators. | 107th cheapest of 377 $1,144 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 keeps a box up all month with no session cap for its $39 Team pool, while Vercel restarts it every 24 hours; boat does both for $26 a month with SSH. | 276th of 368, with limits $145 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 ships a desktop for an agent to see and click; boat streams one at 60fps with a computer-use API. | 235th of 369, with limits $952 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 | 259th of 367, with limits $486 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 | 277th of 346, with limits $468 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 | 234th of 338, with limits $9,960 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 | 283rd of 360, with limits $554 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 | Vercel Sandbox | Unikraft Cloud | boat |
|---|---|---|---|
| Isolation | Firecracker microVM 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 |
| Longest session | 24 hours on Pro and Enterprise, 45 minutes on Hobby; resume starts a new session | No published maximum; instances run until stopped or put in standby | No cap on paid plans (--no-auto-stop); default TTL 1 hour, changeable |
| Sleep and wake | Filesystem snapshot on stop; memory is not kept and there is no wake on request | Standby after a 1 second idle cooldown by default; stateful mode keeps memory and traffic wakes it in milliseconds | Disk saved every minute and on stop; a stopped sandbox costs nothing and boots again on start |
| Machine size | Up to 8 vCPU / 16 GB per sandbox on Pro, 32 vCPU / 64 GB on Enterprise | 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 |
| Docker inside | Yes, with sudo | The Dockerfile becomes the VM image; no container runtime inside is documented | Yes, with root and systemd |
| Nested virtualization | No | Yes, with a per-instance flag, Enterprise only | Yes, /dev/kvm on every plan |
| SSH | No; commands and files go through the SDK and CLI | Not yet; commands and files go through the sandbox plugin and CLI | Yes, into every sandbox |
| Desktop and browser | None; headless Linux only | None built in; you can run your own headless browser from a Dockerfile | 60fps desktop and Chromium, with computer-use and browser-control APIs |
| Coding agents | Claude Code, Codex, OpenCode and pi preinstalled; you start them as commands | None preinstalled; you bring the agent in your own image | Seven agents preinstalled, with an API to prompt, steer and stream events |
| Inbound access | Public URLs for up to 15 ports, no built-in auth; no raw TCP or public IP | Services on its load balancer: HTTP, HTTPS and TLS-wrapped TCP; no public IP per instance | HTTPS URLs for up to 50 ports, token-protected by default; raw TCP; dedicated IPv4 or IPv6 |
| Outbound rules | Allow-all, deny-all or a domain and CIDR allowlist, changeable while running | Network shield filters traffic, Enterprise only, limited access | Open internet, no provider-side allowlist; firewall inside the VM |
| Keys kept outside the sandbox | Credentials brokering injects headers for any HTTPS domain you allow | Network shield can inject secrets, Enterprise only, limited access | Credentials proxy for model providers and any HTTPS API, on every plan; switch a credential to another account when one runs out |
| Regions | 19 regions across the US, Europe, Asia, South America, Africa and Australia | Dallas, Frankfurt, San Francisco, Singapore and Washington DC; more on request | EU only: Germany, Finland, France |
| Self-hosting and GPUs | No self-hosting and no GPUs | Dedicated hosts, on-prem, your own cloud, GPUs and arm64 on Enterprise | No self-hosting, GPUs or arm64 |
Every feature Battleships tracks (43)
| Feature | Vercel Sandbox | 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 | 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 | Yes | Yes | Yes |
| Fork/clone | Yes | Yes | Yes |
| Live fork (no pause) | Yes | Yes | Yes |
| Memory fork | No | 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 | No | 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 | Yes | 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) | No | No | Yes |
| Audit logs | Not published | 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
On the same hpc-sandbox-benchmarks Node.js loop at 4 vCPU / 8 GB, boat did 26.69 runs per second and Vercel Sandbox did 12.96, so boat finished about twice as many runs in the same time. Unikraft Cloud is not in that benchmark, so there is no comparable CPU score for it. Unikraft states cold starts under 10 ms, which is its own figure and measures start time, 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. Unikraft Cloud has 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 | Vercel Sandbox, 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 | $57 · Pro | $39 · Hobby | $20 · $20/mo |
| One agent that never stops 4 vCPU / 8 GB, 50 GB disk, running 24/7 all month | $236 · Pro · 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 | $2,884 · 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 | $828 · Pro | 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 | $3,152 · Pro | Can't run it | $2,000 · $2000/mo · with limits |
Vercel Sandbox: Vercel charges for CPU only while your code uses it, but for memory for the whole time the sandbox runs, plus a small fee per sandbox created and a monthly fee per GB of snapshots. The $20 Pro credit is shared with your other Vercel usage.
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: boat charges a flat price per size, per second, only while the machine runs; a stopped sandbox costs nothing. Plans start at $20 a month, and all of the fee is usage credit.
Limits in those scenarios
For one agent that never stops, Vercel ends each session at 24 hours and running processes start over, while Unikraft's $39 Team pool keeps it up. For 50 agents, sandboxes for your users and 1,000 short jobs at once, Unikraft has no self-serve pool big enough and no published rate, while Vercel fits all three on Pro. boat fits every scenario except the 1,000-job burst, where even its $2,000 plan queues starts above 600 an hour.
| Scenario | Vercel Sandbox | Unikraft Cloud | boat |
|---|---|---|---|
| One coding agent, workdays | None that bite |
| None that bite |
| One agent that never stops |
|
| None that bite |
| 50 agents in parallel | None that bite |
| None that bite |
| Sandboxes for your users | None that bite |
| None that bite |
| 1,000 short jobs at once | None that bite |
|
|
Which one should you use?
Use Vercel Sandbox when
you run many short bursts of untrusted code at high concurrency, want pay-as-you-go rates, or need regions all over the world.
- Big fleets without a sales call. Useful if you run hundreds of sandboxes at once: Vercel Pro allows high concurrency, and Unikraft's self-serve plans stop at 24 running instances.
- Regions all over the world. Useful if your users are spread out: Vercel Sandbox runs in 19 regions, from Virginia to Tokyo, Sydney and Cape Town.
- A firewall on every paid plan. A running sandbox can switch to deny-all or a domain allowlist; on Unikraft, egress filtering is Enterprise only.
Use Unikraft Cloud when
you run small services or headless browsers that sleep most of the time and must wake in milliseconds, or need GPUs, on-prem or your own cloud under an Enterprise contract.
- Millisecond wake and scale-to-zero. Best for many small services that sleep most of the time and must answer the next request in milliseconds, with memory kept.
- No 24-hour session cap. Useful for a box that stays up all month: Unikraft instances run until stopped, while Vercel ends each session at 24 hours.
- Your own hardware on Enterprise. Enterprise teams can get GPUs, arm64, dedicated hosts, on-prem or their own cloud, which Vercel Sandbox does not offer.
Where boat fits
Vercel Sandbox and Unikraft Cloud are both built for short or sleepy work in small microVMs. If your agents work for hours on one machine, with Docker, emulators, a desktop and a browser, look at boat. It also runs fleets of full-size sandboxes on self-serve plans.
A whole machine with SSH
Agents install packages, start databases with Docker and run emulators. Vercel has no /dev/kvm or SSH, and Unikraft has no SSH, no documented Docker inside and nested virtualization only on Enterprise. boat gives root, systemd, Docker, /dev/kvm and SSH on every plan.
A desktop and agents you drive
Neither has a screen, so an agent cannot open the app it built to check it, and you build the layer that prompts and reads each agent yourself. boat streams a 60fps desktop with Chromium and drives seven agents inside from outside through one API.
Long runs at full size
Vercel stops each session at 24 hours and running processes start over. Unikraft has no cap, but its Team pool is 8 GiB in total and 50 agents need an Enterprise quote. boat has no session cap and runs 100 sandboxes from its first paid plan.
Use boat when your agents need a real machine for hours: Docker, emulators, SSH, a desktop and a browser, coding agents you drive from outside, and fleets of full-size sandboxes without a sales call. Compare it one to one: boat vs Vercel Sandbox and boat vs Unikraft Cloud.
Questions people ask
Is Vercel Sandbox cheaper than Unikraft Cloud?
For one agent, Unikraft is cheaper: one coding agent on workdays costs $39 a month on Unikraft against $57 on Vercel, and one that never stops costs $39 against $236. For 50 agents or sandboxes for your users, Vercel fits at $2,884 and $828, while Unikraft needs an Enterprise quote. boat costs $20, $26, $317 and $200 for those four.
Which is faster, Vercel Sandbox or Unikraft Cloud?
For CPU speed there is no fair answer: Vercel did 12.96 runs per second in the hpc-sandbox-benchmarks loop and Unikraft was not measured. For start time, Unikraft is built to cold boot in milliseconds and wake on the next request. boat did 26.69 runs per second in the same benchmark.
Can Vercel Sandbox or Unikraft Cloud run Docker?
Vercel Sandbox can run Docker inside with sudo. Unikraft uses your Dockerfile to build the VM image, and its docs do not describe a container runtime inside a running instance. boat runs Docker with root and systemd, and adds /dev/kvm.
Can either run 24/7?
Unikraft instances have no published session limit and run until stopped or put to sleep. Vercel sessions stop after 24 hours on Pro, and its docs say sandboxes are not designed to run continuously. boat has no session cap on paid plans.
Do they have SSH or a desktop?
No. Both are headless, and you run commands through an SDK, plugin or CLI; Unikraft has announced SSH as coming soon. boat has SSH into every sandbox and a 60fps desktop with Chromium.
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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