CodeSandbox SDK vs Deno Sandbox
Both run code in Firecracker microVMs. CodeSandbox SDK keeps a VM around, hibernating it with its memory and waking it on the next request, while Deno Sandbox is built for short, locked-down runs of up to 30 minutes that start in under 200 ms.
The companies and products
CodeSandbox SDK
CodeSandbox SDK is an API from CodeSandbox, now a Together AI company, that starts sandboxed development VMs on the same infrastructure as the CodeSandbox editor.
Each sandbox is a Firecracker microVM built from a template or any Dockerfile. When it goes idle it hibernates with a memory snapshot, and it resumes or forks from that snapshot in seconds. You drive it from a TypeScript SDK through terminals, commands, files and HTTPS hosts. Together's docs now call it the legacy offering and point new users to its successor, the together-sandbox SDK.
Deno Sandbox
Deno Sandbox is part of Deno Deploy, the hosting platform from the company behind the Deno runtime, and runs untrusted or AI-generated code in Linux microVMs.
Each sandbox is a Firecracker microVM with 2 vCPU, up to 4 GB of memory and a 10 GB disk that is wiped when it ends, created from a TypeScript or Python SDK. Outbound traffic goes through a proxy that can enforce a host allowlist and swap placeholder secrets for real ones. It is built for short runs of agent or user code, and a sandbox can be promoted to a Deno Deploy app.
- Isolation
- Firecracker microVM per sandbox
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. “46th cheapest of 345” means 45 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 | CodeSandbox SDK: price rank | Deno Sandbox: price rank | boat: price rank |
|---|---|---|---|
| Software factory 100 at once · 4 vCPU / 8 GB · 2,200 sessions of 8 h a month Hours of installs, builds and Docker outlast Deno's 30-minute lifetime and 2 vCPU shape; CodeSandbox SDK has no hard cap, and boat adds SSH, /dev/kvm and coding agents built in. | 178th of 367, with limits $1,939 a month | 290th of 367, with limits $5,665 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 needs one that stays up, which CodeSandbox SDK and boat allow and a 30-minute Deno sandbox does not. | 215th of 366, with limits $2,478 a month | 287th of 366, with limits $5,803 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 Both suit short code runs: CodeSandbox SDK wakes a hibernated VM with its memory, Deno starts a fresh one in under 200 ms and bills CPU only while code runs. | 46th cheapest of 345 $642 a month | 141st of 345, with limits $329 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 CodeSandbox SDK wakes a user's sandbox on their next HTTP request and allows 250 at once on Scale; Deno Builder allows 20 at once per region. | 140th of 361, with limits $1,707 a month | 148th of 361, with limits $1,863 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 CodeSandbox SDK can fork a running VM sharing its memory, so many rollouts branch from one warm state; Deno has no fork of a running sandbox. | 348th of 360, with limits $3,861 a month | 122nd of 360, with limits $7,963 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 | 64th cheapest of 364 $1,335 a month | 296th of 364, with limits $1,563 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 jobs that build Docker images or Android apps need Docker and /dev/kvm; CodeSandbox SDK runs Docker, Deno does not document it, and only boat exposes /dev/kvm. | 92nd cheapest of 377 $860 a month | 304th of 377, with limits $731 a month | 4th cheapest of 377 $86 a month |
| 24/7 dev boxes 1 machine 24/7 · 4 vCPU / 8 GB A dev box that stays on all month needs a disk that persists; CodeSandbox SDK and boat keep it, while Deno wipes the root disk when a sandbox ends. | 310th of 368, with limits $240 a month | 179th of 368, with limits $200 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 CodeSandbox SDK nor Deno Sandbox has a desktop; boat streams a Linux desktop at 60fps with Chromium for computer use. | 206th of 369, with limits $691 a month | 280th of 369, with limits $1,583 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 | 251st of 367, with limits $443 a month | 284th of 367, with limits $783 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 | 281st of 346, with limits $508 a month | 286th of 346, with limits $573 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 | 193rd of 338, with limits $7,390 a month | 247th of 338, with limits $11,923 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 | 240th of 360, with limits $326 a month | 251st of 360, with limits $367 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 | CodeSandbox SDK | Deno Sandbox | boat |
|---|---|---|---|
| Isolation | Firecracker microVM with its own kernel | Firecracker microVM with its own kernel | Full VM with its own kernel on dedicated AMD Ryzen 9 9950X hosts |
| Machine size | 2 to 16 cores, up to 32 GB on Scale; up to 64 cores / 128 GB on Enterprise | 2 vCPU fixed, 768 MB to 4 GB memory, 10 GB disk | 4 vCPU / 8 GB by default, up to 16 vCPU / 32 GB on the $100 plan and above |
| Session length | No hard cap; hibernates after an idle timeout of up to one day | Up to 30 minutes; longer work can be promoted to a Deno Deploy app | No cap on paid plans; you set the time to live |
| Disk that persists | Disk kept across hibernation; 20 GB per VM | Root disk wiped when the sandbox ends; opt-in volumes of 300 MB to 20 GB, Chicago only | The whole disk is kept, saved every minute and on stop; a stopped sandbox costs nothing |
| Pause and resume | Hibernates with a memory snapshot; resumes with processes still running | No pause; a sandbox ends with its session | Disk saved on stop; resume boots the machine again |
| Fork | Fork a hibernated sandbox from its snapshot, or a running one sharing its memory | Read-only volume snapshots that new sandboxes boot from; no fork of a running sandbox | Fork a running sandbox with its disk |
| Start time | Wakes from hibernation in seconds; an HTTP request can wake it | Under 200 ms | Boots a full VM |
| Docker and nested virtualization | Docker and root, built from any Dockerfile; nested virtualization not documented | Root access; Docker and nested virtualization not documented | Docker, systemd and /dev/kvm for Android emulators and VMs |
| Shell access | Terminals, commands and files through the SDK; no SSH | SSH and a VS Code editor in the browser | SSH, plus exec and files over the API |
| Inbound access | HTTPS host per port, public by default, signed tokens for private hosts | HTTPS URL per exposed port, public without authentication | HTTPS URLs for up to 50 ports, token-protected by default; raw TCP |
| Outbound rules | No documented host allowlist | Host allowlist per sandbox, enforced by a proxy outside the VM | Open internet, no provider-side allowlist |
| Keeping API keys out of the sandbox | Secrets passed in as environment variables | Secrets swapped in on outbound requests to approved hosts; the sandbox only sees a placeholder | Credentials proxy for model providers and any HTTPS API; switch a credential to another account when credits run out |
| Desktop and coding agents | No desktop; run your own agent through the command API | No desktop; a root image with Claude Code, run through shell commands | Linux desktop at 60fps with Chromium; seven agents preinstalled with a prompt, steer and events API |
| Regions | A country hint steers scheduling, for example to Europe, but placement is not guaranteed | Amsterdam and Chicago | EU only (Germany, Finland, France) |
Every feature Battleships tracks (43)
| Feature | CodeSandbox SDK | Deno Sandbox | boat |
|---|---|---|---|
| Full VM (own kernel) | Yes | Yes | Yes |
| Docker inside | Yes | Not published | Yes |
| Nested virtualization | No | No | 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 | Yes | Yes |
| Persistent disk | Yes | Yes | Yes |
| Pause/resume | Yes | No | Yes |
| Automatic snapshots | Yes | No | Yes |
| Fork/clone | Yes | No | Yes |
| Live fork (no pause) | Yes | No | Yes |
| Memory fork | Yes | No | No |
| Custom image (Docker or snapshot) | Yes | Yes | Yes |
| ≥24 h sessions | Yes | No | Yes |
| Idle auto-stop | Yes | No | No |
| Wake on request | Yes | No | No |
| HTTPS preview URLs | Yes | Yes | Yes |
| Raw TCP inbound | No | No | Yes |
| Public IPv4 | No | No | No |
| Egress allowlist | No | Yes | No |
| Secret proxy | No | Yes | Yes |
| Secret proxy for any API | No | Yes | Yes |
| Preinstalled agents | No | Yes | Yes |
| Agent harness API | No | No | Yes |
| MCP server | No | No | No |
| GPU | No | No | No |
| Windows | No | No | No |
| Arm64 | No | No | No |
| Self-hosting | No | No | No |
| BYOC | No | No | No |
| Open source | No | No | No |
| Scoped API keys | Not published | Not published | Yes |
| Spend limits | Not published | Yes | Yes |
| Usage per sandbox (API) | No | No | Yes |
| Audit logs | Not published | Not published | No |
| SSO | Yes | No | No |
| SOC 2 | Yes | Yes | No |
| HIPAA | No | Yes | No |
| EU data residency | No | Yes | Yes |
| Zero data retention | Not published | Not published | Yes |
Performance
There is no comparable CPU measurement for CodeSandbox SDK or Deno Sandbox. boat did 26.69 runs per second on the StarSling hpc-sandbox-benchmarks Node.js loop at 4 vCPU / 8 GB, on dedicated AMD Ryzen 9 9950X hosts; neither of the other two was in that run, and Deno's fixed 2 vCPU shape could not run the 4 vCPU test as set up.
Node.js build-and-test loop at 4 vCPU / 8 GB, higher is better. Measured with the open hpc-sandbox-benchmarks suite. CodeSandbox SDK and Deno Sandbox 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 | CodeSandbox SDK, a month | Deno Sandbox, 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 | $193 · Scale | $53 · Pro · with limits | $20 · $20/mo |
| One agent that never stops 4 vCPU / 8 GB, 50 GB disk, running 24/7 all month | $341 · Scale | $200 · Builder · with limits | $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 | $2,500 · Scale | $2,779 · Builder · with limits | $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 | $815 · Scale · with limits | $783 · Builder · with limits | $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 | $1,632 · Scale · with limits | $1,563 · Builder · with limits | $2,000 · $2000/mo · with limits |
CodeSandbox SDK: You buy VM credits and each size burns a fixed number per hour, billed per started minute while the VM runs, including the idle time before it hibernates. Teams pay a $170 monthly Scale platform fee on top, which is not usage credit, and a hibernated VM costs nothing.
Deno Sandbox: Sandboxes need Pro at $20 a month or Builder at $200 a month; the fee is not credit but includes CPU, memory and egress allowances shared with Deno Deploy apps. Past those, CPU is $0.10 per hour of active CPU and memory $0.025 per GiB-hour for the whole life of the sandbox.
Deno Sandbox: 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
Deno Sandbox fits none of the five scenarios as written: a sandbox lives up to 30 minutes, is fixed at 2 vCPU and 4 GB, and Builder allows 20 at once per region. CodeSandbox SDK fits the workday agent, the always-on agent and 50 agents in parallel, but its Scale plan caps at 250 VMs at once, so the user-sandboxes and 1,000-job scenarios need Enterprise, and its disk past 20 GB and egress are not priced. boat fits four of the five; at 1,000 short jobs at once its top plan queues starts, so none of the three fits that one without a custom plan.
| Scenario | CodeSandbox SDK | Deno Sandbox | boat |
|---|---|---|---|
| One coding agent, workdays |
|
| None that bite |
| One agent that never stops |
|
| None that bite |
| 50 agents in parallel |
|
| None that bite |
| Sandboxes for your users |
|
| None that bite |
| 1,000 short jobs at once |
|
|
|
Which one should you use?
Use CodeSandbox SDK when
your sandboxes sleep between visits and should wake on the next HTTP request with their memory intact, or need more than 2 vCPU for longer than 30 minutes, and you are fine building on what Together now calls its legacy SDK.
- VMs that sleep and wake with their memory. Useful for previews and code runs used in bursts: an HTTP request wakes a hibernated VM with its processes still running.
- No 30-minute ceiling and bigger machines. Fits longer jobs: a VM runs until it goes idle, with up to 16 cores on Scale and 64 on Enterprise.
- Forks that share memory. Good for branching many runs, such as rollouts or test variants, from one warm running state.
Use Deno Sandbox when
you run short pieces of untrusted code that must start in milliseconds, reach only the hosts you allow, or run in the US, especially if you already deploy on Deno Deploy.
- Locked-down outbound traffic. Useful for untrusted code: each sandbox can be limited to a list of hosts, and secrets stay outside the VM.
- Starts in under 200 ms. Good for one sandbox per request: it starts fast and CPU bills only while code is running.
- A US region and Deno Deploy. Fits teams on Deno Deploy who want Chicago or Amsterdam and a path from sandbox to a live app.
Where boat fits
If what you are really running is agents that work for hours, look at boat. CodeSandbox SDK and Deno Sandbox are both good at short code runs, but neither gives an agent a full machine with SSH, nested virtualization, a desktop and its coding harness already set up.
A full machine with KVM and SSH
Neither documents /dev/kvm, so Android emulators and VM-based tests cannot start. CodeSandbox SDK has no SSH, and Deno is fixed at 2 vCPU and 4 GB, which big builds outgrow. boat runs Docker, systemd and /dev/kvm on up to 16 vCPU.
A disk that stays, without a clock
A Deno sandbox ends after 30 minutes and wipes its root disk, so long tasks must be split and rebuilt. CodeSandbox SDK keeps the disk but bills the idle time before it hibernates. boat saves the disk every minute and a stopped sandbox costs nothing.
Agents, desktop and hosting built in
On both you build the agent harness and browser yourself, and hosts are public by default. boat ships seven agents you drive from outside, a 60fps desktop with Chromium, and token-protected HTTPS on 50 ports plus raw TCP.
Use boat when your agents do real work for hours: installs, builds, Docker, emulators, a browser and servers other people reach, on a full machine whose disk is still there tomorrow and whose agent and keys are already set up. Compare it one to one: boat vs CodeSandbox SDK and boat vs Deno Sandbox.
Questions people ask
Is CodeSandbox SDK cheaper than Deno Sandbox?
Deno often looks cheaper, but it fits none of the five scenarios as written. For 50 agents in parallel, CodeSandbox SDK comes to $2,500 a month and fits, while Deno Builder comes to $2,779 a month and caps at 20 at once and 30 minutes each. boat fits that one at $317 a month.
Which is faster, CodeSandbox SDK or Deno Sandbox?
Neither has a comparable CPU measurement, so there is no fair speed ratio. Deno says a sandbox starts in under 200 ms, while CodeSandbox SDK resumes a hibernated VM from a memory snapshot in seconds with processes still running.
Can CodeSandbox SDK or Deno Sandbox run Docker?
CodeSandbox SDK runs Docker with root and builds sandboxes from any Dockerfile. Deno's docs give root access but do not say Docker works, and neither documents nested virtualization. boat runs Docker and systemd and exposes /dev/kvm.
How long can a sandbox run on each?
A Deno sandbox lives up to 30 minutes, and longer work can be promoted to a Deno Deploy app. CodeSandbox SDK has no hard cap and hibernates after an idle timeout of up to one day. boat has no cap on paid plans.
Is CodeSandbox SDK still maintained?
CodeSandbox is now part of Together AI. Together's docs call the CodeSandbox-based SDK deprecated and name together-sandbox as its successor, while self-serve sign-up still runs through CodeSandbox.
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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