CodeSandbox SDK vs Freestyle
Both pause a sandbox with its memory and wake it on the next request. CodeSandbox SDK runs Firecracker microVMs you drive through a TypeScript SDK and that Together now calls legacy, while Freestyle runs full KVM VMs with systemd, nested virtualization, agent CLIs and a default-deny firewall.
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.
Freestyle
Freestyle sells full Linux virtual machines for AI agents, built for long running, complex tasks.
Each Freestyle VM is a KVM virtual machine with its own kernel, booted from an Ubuntu base snapshot with systemd, Docker and coding agent CLIs preinstalled. VMs can be paused with their memory, snapshotted while running, forked and woken by the next request, and every VM starts behind a default-deny firewall. It is built for teams that give each agent or each user its own machine, driven from a TypeScript SDK, a CLI or an API.
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 | Freestyle: price rank | boat: price rank |
|---|---|---|---|
| Software factory 100 at once · 4 vCPU / 8 GB · 2,200 sessions of 8 h a month Freestyle runs systemd, Docker and emulators where CodeSandbox SDK documents no nested virtualization, and boat adds CPUs that did about 2.8 times Freestyle's work. | 178th of 367, with limits $1,939 a month | 241st of 367, with limits $3,311 a month | 3rd cheapest of 367 $634 a month |
| Always-on AI employees 50 machines 24/7 · 2 vCPU / 4 GB | 215th of 366, with limits $2,478 a month | 263rd of 366, with limits $4,195 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 that sleep between calls and wake with their memory, and the two rank close together here. | 46th cheapest of 345 $642 a month | 40th cheapest of 345 $482 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 Freestyle fits this scenario and CodeSandbox SDK does not, because Scale stops at 250 VMs at once; boat fits it too and gives each user a desktop and raw TCP. | 140th of 361, with limits $1,707 a month | 16th cheapest of 361 $1,358 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 can fork a running sandbox from its memory, which suits rollouts that branch from one state. | 348th of 360, with limits $3,861 a month | 107th of 360, with limits $6,600 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 | 53rd cheapest of 364 $1,046 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 fits CI runs fully here, while Freestyle's docs send sustained heavy CPU work elsewhere; boat runs builds on dedicated AMD Ryzen 9 9950X hosts. | 92nd cheapest of 377 $860 a month | 168th of 377, with limits $625 a month | 4th cheapest of 377 $86 a month |
| 24/7 dev boxes 1 machine 24/7 · 4 vCPU / 8 GB Freestyle fits a dev box kept all month, while CodeSandbox SDK caps each VM at a 20 GB disk with no published price for more. | 310th of 368, with limits $240 a month | 98th cheapest of 368 $151 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: CodeSandbox SDK has none and Freestyle has guides to install one, while boat streams a 60fps desktop with computer use built in. | 206th of 369, with limits $691 a month | 234th of 369, with limits $940 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 CodeSandbox SDK offers a headless Chromium template and Freestyle a guide to install Chromium, while boat has Chromium on a full desktop in every sandbox. | 251st of 367, with limits $443 a month | 257th of 367, with limits $482 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 | 278th of 346, with limits $482 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 | 183rd of 338, with limits $6,560 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 | 272nd of 360, with limits $482 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 | Freestyle | boat |
|---|---|---|---|
| Isolation | Firecracker microVM with its own kernel | Full KVM VM with its own kernel on bare metal servers | Full VM with its own kernel on dedicated AMD Ryzen 9 9950X hosts |
| CPU benchmark (4 vCPU / 8 GB) | Not measured | 9.64 runs/s | 26.69 runs/s |
| Root, systemd and Docker | Docker and root, built from any Dockerfile | Root, systemd as pid 1, Docker from boot | Root, systemd and Docker |
| Nested virtualization | Not documented | Yes, full KVM support | Yes, /dev/kvm for Android emulators and VMs |
| Biggest machine | 16 cores / 32 GB on Scale, 64 / 128 GB on Enterprise | 32 vCPU / 64 GiB on Pro, 64 / 128 with custom limits | 16 vCPU / 32 GB on the $100 plan and above |
| Pause and resume | Hibernates with a memory snapshot; resumes with processes running | Pause saves memory and disk; the same processes resume | Disk saved every minute and on stop; resume boots the machine again |
| Fork | Fork a hibernated sandbox, or a running one sharing its memory | Clone a running VM without pausing it; snapshots hold memory and disk | Fork a running sandbox with its disk |
| Wake on request | Yes, an HTTP request to a host wakes it | Yes, a paused VM resumes on the next traffic | No; a stopped sandbox is started by API |
| Inbound access | HTTPS host per port, public by default; no raw TCP | HTTPS on style.dev names or your own domain, forward auth, other public protocols | HTTPS URLs for up to 50 ports, token-protected by default; raw TCP |
| Outbound rules | No provider-side allowlist | Default-deny firewall with allow rules by IP, VM, VPC or domain | Open internet, no provider-side allowlist |
| Coding agents | Run your own agent through the command API | claude, codex, opencode and openclaw preinstalled, driven through exec | Seven agents preinstalled, with a prompt, steer and events API |
| Desktop and browser | No desktop; a headless Chromium template | Guides to install GNOME or Xvfb, VNC and Chromium yourself | Linux desktop streamed at 60fps, Chromium and computer use built in |
| Keeping API keys out of the sandbox | Secrets passed in as environment variables | Credentials injected at the edge for HTTPS, Postgres and S3 | Credentials proxy for model providers and any HTTPS API, with account switching |
| Regions | A country hint, such as a cluster in Europe, but no guarantee | Not listed; the docs name a San Jose, US data center | EU only (Germany, Finland, France), zero data retention |
Every feature Battleships tracks (43)
| Feature | CodeSandbox SDK | Freestyle | 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 | No | Yes |
| Computer-use API | No | No | Yes |
| SSH | No | Yes | 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 | Yes | 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 | Yes | 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 | Yes | Yes |
| Spend limits | Not published | Not published | Yes |
| Usage per sandbox (API) | No | No | Yes |
| Audit logs | Not published | Yes | No |
| SSO | Yes | Yes | No |
| SOC 2 | Yes | Not published | No |
| HIPAA | No | Not published | No |
| EU data residency | No | No | Yes |
| Zero data retention | Not published | Not published | Yes |
Performance
On the hpc-sandbox-benchmarks Node.js loop at 4 vCPU / 8 GB, Freestyle did 9.64 runs per second and boat did 26.69, about 2.8 times the work in the same time. CodeSandbox SDK has no comparable CPU measurement. This test measures CPU speed only, not start time.
Node.js build-and-test loop at 4 vCPU / 8 GB, higher is better. Measured with the open hpc-sandbox-benchmarks suite. CodeSandbox SDK 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 | CodeSandbox SDK, a month | Freestyle, 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 | $27 · Free | $20 · $20/mo |
| One agent that never stops 4 vCPU / 8 GB, 50 GB disk, running 24/7 all month | $341 · Scale | $159 · Free | $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 | $2,139 · 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 | $815 · Scale · with limits | $581 · Pro | $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 | $1,305 · Pro · 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. Scale adds a $170 monthly platform fee that is not usage credit.
Freestyle: Freestyle bills per second for the vCPU, RAM and disk allocated to a VM, busy or idle, after monthly allowances. Hobby and Pro set a $50 or $500 monthly minimum that counts as usage, and a paused VM bills only for storage.
Freestyle: 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
CodeSandbox SDK's Scale plan allows 250 VMs at once, so it does not fit the user-sandboxes scenario with 300 at once, and each VM has a 20 GB disk with no published price for more. Freestyle Pro allows 400 at once, which covers 300 user sandboxes but not 1,000 short jobs. On Freestyle Free the monthly allowances are hard stops, and there is no idle timeout unless you set one. boat has no concurrency cap at these sizes, but even its $2,000 plan queues starts above 90 a minute.
| Scenario | CodeSandbox SDK | Freestyle | boat |
|---|---|---|---|
| One coding agent, workdays |
| None that bite | None that bite |
| One agent that never stops |
| None that bite | 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 |
|
|
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Which one should you use?
Use CodeSandbox SDK when
your sandboxes are previews or code runs built from a Dockerfile that sleep between visits and wake on the next HTTP request, and you are fine building on what Together now calls its legacy SDK.
- Sleeps cheaply between visits. A hibernated VM costs nothing, and the next HTTP request wakes it with its memory and running processes.
- Built from any Dockerfile. Teams with an existing Dockerfile can turn it into a sandbox template without building a VM snapshot.
- Per-minute credits, no allocation billing. You pay credits only while a VM runs, and no storage fee is documented for a hibernated one.
Use Freestyle when
you want full VMs with systemd and nested virtualization that pause with their memory, a default-deny firewall per VM, or more than 250 sandboxes at once.
- A full machine for agents. Each VM has systemd, Docker, nested virtualization and agent CLIs ready, so emulators and services run as on a server.
- Network controls per VM. Every VM starts behind a default-deny firewall, with allow rules by IP, VM, VPC or exact domain.
- Bigger machines and more at once. Pro allows 400 VMs at once and machines up to 32 vCPU / 64 GiB, larger with custom limits.
Where boat fits
Both are strongest at sandboxes that sleep and wake with their memory. If your agents instead work for hours on builds, tests, Docker and a browser, boat gives each one a full VM on faster CPUs with a desktop and the agents already set up.
Faster CPUs for builds and tests
Freestyle did 9.64 runs per second on the CPU benchmark and boat did 26.69, so every install and test waits almost three times as long there. CodeSandbox SDK has no comparable measurement.
A desktop and browser, ready
CodeSandbox SDK has no desktop and Freestyle leaves you to install GNOME, VNC and Chromium. boat streams a 60fps desktop with Chromium and computer use in every sandbox, so the agent can use web pages on day one.
Agents driven from outside
On CodeSandbox SDK you install and run your own agent; on Freestyle you start a CLI through exec and parse its output. boat lets you prompt, steer and follow the agents inside through one API, and switch a credential when credits run out.
Use boat when your agents do real work for hours: builds, tests, Docker, emulators, a desktop and a browser, on fast CPUs, with an API to drive the agents inside from outside. Compare it one to one: boat vs CodeSandbox SDK and boat vs Freestyle.
Questions people ask
Is CodeSandbox SDK cheaper than Freestyle?
Not in these scenarios. One coding agent on workdays comes to $193 a month on CodeSandbox SDK against $27 on Freestyle, and one agent running all month is $341 against $159. boat is $20 and $26 for the same two.
Which is faster, CodeSandbox SDK or Freestyle?
Freestyle did 9.64 runs per second on the hpc-sandbox-benchmarks CPU test at 4 vCPU / 8 GB, and CodeSandbox SDK was not measured, so there is no direct CPU comparison. boat did 26.69 on the same test.
Can CodeSandbox SDK and Freestyle run Docker?
Both run Docker inside the sandbox. Freestyle also has systemd and full KVM support for Android emulators and VMs, while CodeSandbox SDK does not document nested virtualization.
Do both pause a sandbox with its memory?
Yes. CodeSandbox SDK hibernates with a memory snapshot and Freestyle pauses with memory and disk, and both can wake on the next request. boat saves the disk every minute instead, and resuming boots the machine again.
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.
How many sandboxes can run at once?
CodeSandbox SDK's Scale plan allows 250 VMs at once and Freestyle Pro allows 400, with more on Enterprise for both. Neither fits 1,000 short jobs at once on a self-serve plan.
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