CodeSandbox SDK vs exe.dev
CodeSandbox SDK starts Firecracker VMs that hibernate with their memory when idle and wake on the next HTTP request, driven from a TypeScript SDK. exe.dev rents persistent KVM VMs you reach over SSH, from a reserved pool or billed per second, with coding agents preinstalled and nine regions to pick from.
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.
exe.dev
exe.dev, made by Bold Software, Inc., rents Linux VMs for developers and AI agents that you reach over SSH and HTTPS.
You reserve a pool of vCPUs and memory, and your VMs share it; you can also start standalone VMs billed by the second. Each VM is KVM-isolated (they use Cloud Hypervisor), boots from a container image in about two seconds, and has root, systemd and Docker. It comes with Claude Code, Codex, Pi and exe.dev's own Shelley agent, and is aimed at developers who want a persistent dev box or a sandbox for their agents.
- Company
- Bold Software, Inc.
- Preinstalled agents
- claude, codex, pi and the Shelley web agent
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 | exe.dev: price rank | boat: price rank |
|---|---|---|---|
| Software factory 100 at once · 4 vCPU / 8 GB · 2,200 sessions of 8 h a month | 178th of 367, with limits $1,939 a month | 253rd of 367, with limits $3,701 a month | 3rd cheapest of 367 $634 a month |
| Always-on AI employees 50 machines 24/7 · 2 vCPU / 4 GB exe.dev fits an always-on assistant fully with a VM that runs until you stop it; CodeSandbox SDK gets costly running all month, and boat adds a desktop and an agent API. | 215th of 366, with limits $2,478 a month | 15th cheapest of 366 $3,833 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 CodeSandbox SDK fits short code runs well, since VMs hibernate between runs and wake fast; exe.dev is built for long-lived VMs, not many tiny runs. | 46th cheapest of 345 $642 a month | 235th of 345, with limits $175 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 Neither fits 300 user sandboxes at once on its self-serve plans (250 on CodeSandbox SDK Scale, 50 on exe.dev Personal); boat does. | 140th of 361, with limits $1,707 a month | 257th of 361, with limits $1,226 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's memory forks let rollouts branch from one running state, while exe.dev's cp copies only the disk. | 348th of 360, with limits $3,861 a month | 265th of 360, with limits $5,250 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 CodeSandbox SDK fits agent evals, with forks from one warm memory state; exe.dev's 50 VM cap on Personal gets in the way, and boat fits at higher concurrency. | 64th cheapest of 364 $1,335 a month | 283rd of 364, with limits $1,050 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 CodeSandbox SDK bills only while jobs run, which suits CI better than an exe.dev pool that bills whether jobs run or not; boat adds /dev/kvm for emulator builds. | 92nd cheapest of 377 $860 a month | 288th of 377, with limits $504 a month | 4th cheapest of 377 $86 a month |
| 24/7 dev boxes 1 machine 24/7 · 4 vCPU / 8 GB exe.dev makes a good 24/7 dev box with SSH and a pool billed flat; CodeSandbox SDK has no SSH and bills credits for every running minute, and boat fits too with a desktop in the browser. | 310th of 368, with limits $240 a month | 25th cheapest of 368 $35 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 exe.dev has a desktop for computer-use agents; boat streams one at 60fps. | 206th of 369, with limits $691 a month | 240th of 369, with limits $1,055 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 | 130th of 367, with limits $530 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 | 124th of 346, with limits $278 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 | 166th of 338, with limits $5,490 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 | 60th of 360, with limits $263 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 | exe.dev | boat |
|---|---|---|---|
| Isolation | Firecracker microVM with its own kernel | KVM VM with Cloud Hypervisor; you can't choose the kernel | Full VM with its own kernel on dedicated AMD Ryzen 9 9950X hosts |
| Pause and resume | Hibernates with a memory snapshot; resumes with processes still running | Disk persists and is streamed to a second server; no snapshots | Disk is saved every minute and on stop; resume boots the machine again |
| Fork | Fork a hibernated sandbox from its snapshot, or a running one sharing its memory | cp copies a VM's disk and config into a new VM | Fork a running sandbox with its disk; named snapshots as templates |
| Wake on request | Yes; an HTTP request to a host wakes a hibernated VM | No; VMs run until you stop them | No; a stopped sandbox is started by API |
| Shell access | Terminals, commands and files through the SDK; no SSH | SSH, brokered through exe.dev | SSH, plus exec and files over the API |
| Custom images | Built from a template or any Dockerfile | Boot from your own Docker image | Templates from named snapshots; no Dockerfile or OCI images |
| Docker and root | Docker and root | Docker, systemd and root | Docker, systemd and root |
| Nested virtualization | Not documented | Enterprise only | Yes, /dev/kvm on every plan |
| Coding agents | Run your own agent through the command API | Claude Code, Codex, Pi and Shelley preinstalled; only Shelley takes prompts by API | Claude Code, Codex and five more preinstalled, with a prompt, steer and events API |
| Desktop and browser | No desktop; a headless Chromium template | Headless; no desktop or screen streaming | Linux desktop streamed at 60fps, Chromium and computer-use tools |
| Inbound access | HTTPS host per port, public by default; no raw TCP or public IP | HTTPS proxy for ports 3000 to 9999 and SSH; no public IP or raw TCP | HTTPS URLs for up to 50 ports, token-protected by default; raw TCP; dedicated IPv6 or IPv4 |
| Keeping API keys out of the sandbox | Secrets passed in as environment variables | Integrations inject secrets at the network edge for any HTTP host | Credentials proxy for model providers and any HTTPS API; switch accounts when credits run out |
| Regions | No region choice; a country hint steers scheduling but is not guaranteed | 9 regions in the US, Europe, Asia and Australia | EU only: Germany, Finland, France |
| Biggest machine | Up to 16 cores / 32 GB on Scale, 64 cores / 128 GB on Enterprise | Personal pools up to 16 vCPU | Up to 16 vCPU / 32 GB on the $100 plan and above |
Every feature Battleships tracks (43)
| Feature | CodeSandbox SDK | exe.dev | boat |
|---|---|---|---|
| Full VM (own kernel) | Yes | Yes | Yes |
| Docker inside | Yes | Yes | Yes |
| Nested virtualization | No | Yes | Yes |
| Root | Yes | Yes | Yes |
| Systemd | Not published | Yes | Yes |
| Desktop GUI | No | No | Yes |
| Browser | No | Yes | Yes |
| Computer-use API | No | No | Yes |
| SSH | No | Yes | 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 | No | No |
| Custom image (Docker or snapshot) | Yes | Yes | Yes |
| ≥24 h sessions | Yes | Yes | 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 | No | No |
| Secret proxy | No | Yes | Yes |
| Secret proxy for any API | No | Yes | Yes |
| Preinstalled agents | No | Yes | Yes |
| Agent harness API | No | Yes | Yes |
| MCP server | No | Yes | No |
| GPU | No | No | No |
| Windows | No | No | No |
| Arm64 | No | No | No |
| Self-hosting | No | No | No |
| BYOC | No | Yes | No |
| Open source | No | No | No |
| Scoped API keys | Not published | Yes | Yes |
| Spend limits | Not published | Not published | Yes |
| Usage per sandbox (API) | No | Yes | Yes |
| Audit logs | Not published | Not published | No |
| SSO | Yes | Yes | No |
| SOC 2 | Yes | No | No |
| HIPAA | No | No | No |
| EU data residency | No | Yes | Yes |
| Zero data retention | Not published | Not published | Yes |
Performance
Neither CodeSandbox SDK nor exe.dev is in the hpc-sandbox-benchmarks run, so there is no comparable CPU measurement for either. boat did 26.69 runs per second on that Node.js loop at 4 vCPU / 8 GB, on dedicated AMD Ryzen 9 9950X hosts. We don't guess how the other two would score.
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 exe.dev 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 | exe.dev, 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 | $35 · Personal | $20 · $20/mo |
| One agent that never stops 4 vCPU / 8 GB, 50 GB disk, running 24/7 all month | $341 · Scale | $35 · Personal | $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 | $1,848 · Personal | $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 | $530 · Personal · 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 | $1,050 · Personal · 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 idle time before it hibernates. The Scale plan adds a $170 monthly platform fee that is not usage credit, and a hibernated VM costs nothing.
exe.dev: Pools are reserved capacity your VMs share, billed the same whether they are busy or idle: Personal is $35 a month for 4 vCPU / 8 GiB. Standalone VMs bill per second at $0.105 per 2 vCPU / 4 GiB per hour.
exe.dev: Plans start at $20 a month, and the whole fee is usage credit. Sandboxes bill per second while they run, and a stopped sandbox costs nothing and keeps its disk.
Limits in those scenarios
CodeSandbox SDK's Scale plan allows 250 VMs at once and exe.dev Personal allows 50, so neither fits the 300 user sandboxes or the 1,000 short jobs at once. CodeSandbox SDK gives each VM a 20 GB disk and does not publish the price for more disk or for egress. An exe.dev pool bills whether it is used or not. boat fits 300 at once, but its start limits queue a burst of 1,000 short jobs even on the $2,000 plan.
| Scenario | CodeSandbox SDK | exe.dev | boat |
|---|---|---|---|
| One coding agent, workdays |
|
| 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 |
| 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, and you are fine building on what Together now calls its legacy SDK.
- Memory hibernation and wake on request. Good for previews and code runs that sleep between visits: an HTTP request wakes the VM with its processes still running.
- Forks that share memory. Useful for branching many rollouts or test variants from one warm running state instead of booting each one fresh.
- Pay only while a VM runs. Credits burn per started minute while a VM runs, and a hibernated VM costs nothing, which suits bursty work.
Use exe.dev when
you want a persistent VM you SSH into, billed as a flat pool, in a region near users outside Europe.
- A persistent box you SSH into. Good for developers who want a VM that runs until they stop it, with SSH, systemd and a flat monthly pool.
- Regions around the world. Useful if your users are far from Europe: exe.dev runs in nine regions across the US, Europe, Asia and Australia.
- Agents and team controls included. Claude Code, Codex and Pi come preinstalled, and the Work plan covers a whole team with SSO and roles.
Where boat fits
If you are weighing CodeSandbox SDK against exe.dev to run coding agents, look at boat too. It gives each agent a full VM with SSH, /dev/kvm, a 60fps desktop and its agent already set up behind one API, with state saved every minute and no cap on how long a paid sandbox runs.
A screen your agents can use
Neither CodeSandbox SDK nor exe.dev has a desktop, so a computer-use agent has nothing to look at. On both you build and stream a desktop yourself; boat streams one at 60fps with Chromium.
Drive agents inside from outside
CodeSandbox SDK leaves the agent harness to you, and exe.dev only takes API prompts for its own Shelley agent. boat lets you prompt, steer and stream events from Claude Code, Codex and others through one API.
Emulators and nested VMs on every plan
Android emulator builds and VM-based tests need /dev/kvm. CodeSandbox SDK does not document it, and exe.dev only offers it on Enterprise; boat has it on every plan.
Use boat when your agents do real work for hours: builds, Docker, emulators, a desktop and a browser, with state saved every minute and one API to drive agents inside from outside. Compare it one to one: boat vs CodeSandbox SDK and boat vs exe.dev.
Questions people ask
Is CodeSandbox SDK cheaper than exe.dev?
Not in our scenarios. One coding agent on workdays comes to $193 a month on CodeSandbox SDK against $35 on exe.dev, and 50 agents in parallel to $2,500 against $1,848. boat is lower than both in four of the five scenarios.
Which is faster, CodeSandbox SDK or exe.dev?
Neither has a comparable CPU measurement, since neither is in the hpc-sandbox-benchmarks run. boat scored 26.69 runs per second on that test at 4 vCPU / 8 GB.
Can I SSH into CodeSandbox SDK like exe.dev?
No. CodeSandbox SDK connects through its SDK, Node and browser clients, with terminals, commands and files. exe.dev and boat both give you SSH.
Can CodeSandbox SDK and exe.dev run Docker?
Yes, both run Docker with root inside the VM. For Android emulators or nested VMs, exe.dev needs Enterprise and CodeSandbox SDK does not document it, while boat has /dev/kvm on every plan.
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.
Do CodeSandbox SDK or exe.dev have a desktop for computer use?
No. Both are headless. boat streams a 60fps desktop with Chromium and has APIs for computer use and browser control.
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