Modal vs Upstash Box
Modal runs short-lived gVisor sandboxes inside a big AI compute platform with GPUs and regions around the world, and each one ends within 24 hours. Upstash Box gives each agent a light container in the US that pauses when idle, keeps its files and wakes on the next request.
The companies and products
Modal
Modal is a serverless cloud for AI work: inference, training, batch jobs and sandboxed code, all driven from Python, TypeScript or Go code.
Modal Sandboxes are containers you create from code, run commands in, and then terminate. By default they run under gVisor, a user-space kernel from Google; since October 2026 you can also pick a VM runtime with its own Linux kernel for Docker and FUSE (Battleships tracks that as a separate card, Modal VM Sandboxes). It suits teams that already run models on Modal and want short-lived, scalable code execution next to their GPUs.
Upstash Box
Upstash Box is a cloud computer for AI agents from Upstash, the company known for serverless Redis, Vector and QStash.
Each box is a Docker container with its own filesystem, shell, git and an optional coding agent such as Claude Code, Codex or OpenCode, which you drive from TypeScript or Python SDKs. A box pauses when it sits idle, keeps its files, and you pay for the CPU it actually uses. Upstash built it to run its own Context7 service and opened it to everyone in March 2026.
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. “19th cheapest of 345” means 18 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 | Modal: price rank | Upstash Box: 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 needs Docker and a disk that lasts, which Modal's default sandbox and Upstash's container both lack, while boat has both in every sandbox. | Can't run it | 61st of 367, with limits $464 a month | 3rd cheapest of 367 $634 a month |
| Always-on AI employees 50 machines 24/7 · 2 vCPU / 4 GB An always-on agent hits Modal's 24-hour sandbox limit, while Upstash can keep a box on all month and boat has no session cap on paid plans. | 196th of 366, with limits $1,924 a month | 103rd of 366, with limits $475 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 fit short code runs well: Upstash Box ranks 10th because an idle box costs no CPU, Modal follows at 19th with fast starts, and boat's start limits hold it back. | 19th cheapest of 345 $181 a month | 10th cheapest of 345 $119 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 Giving each user a sandbox they come back to suits Upstash's paused boxes and boat's free stops better than Modal, where every sandbox ends within a day. | 11th cheapest of 361 $811 a month | 2nd cheapest of 361 $222 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 RL rollouts launch huge numbers of short sandboxes at once, which is what Modal is built for, while Upstash Box ranks 352nd here. | 5th cheapest of 360 $19,038 a month | 352nd of 360, with limits $8,068 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 | 59th cheapest of 364 $1,244 a month | 52nd cheapest of 364 $1,011 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 need Docker inside, which boat has in every sandbox, Modal only on its VM runtime, and Upstash not at all. | 126th cheapest of 377 $1,793 a month | 120th cheapest of 377 $1,520 a month | 4th cheapest of 377 $86 a month |
| 24/7 dev boxes 1 machine 24/7 · 4 vCPU / 8 GB A flat-price keep-alive box makes Upstash a good light dev box, while a Modal sandbox resets its packages within 24 hours. | 138th of 368, with limits $23 a month | 10th cheapest of 368 $20 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: Modal offers none, Upstash has a headless browser only, and boat streams a full Linux desktop at 60fps. | 98th of 369, with limits $183 a month | 73rd of 369, with limits $76 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 | 177th of 367, with limits $136 a month | 49th of 367, with limits $38 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 | 267th of 346, with limits $394 a month | 37th cheapest of 346 $400 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 | 223rd of 338, with limits $8,795 a month | 200th of 338, with limits $8,000 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 | Can't run it | 225th of 360, with limits $259 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 Modal has GPUs from T4 to B300, and neither Upstash Box nor boat has any, so Modal is the pick for GPU jobs. | 19th cheapest of 98 $1,187 a month | 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 | Modal | Upstash Box | boat |
|---|---|---|---|
| Isolation | gVisor by default; VM runtime with its own kernel available | Docker container per box on AWS | Full VM with its own kernel on dedicated AMD Ryzen 9 9950X hosts |
| Docker inside | Only with the VM runtime | Not documented; the box is itself a Docker container | Yes, Docker and systemd in every sandbox |
| Nested virtualization | VM runtime only, Team and Enterprise plans, on request | No VM support documented | Yes, /dev/kvm for Android emulators and VMs |
| Stop and resume | No paused state; a finished sandbox is gone, only Volumes keep files | Pauses itself when idle and keeps its files; storage bills while paused | Disk saved every minute and on stop; a stopped sandbox costs nothing |
| Longest session | 24 hours (default 5 minutes) | No documented cap; keep-alive boxes stay on all month | No cap on paid plans |
| Wake on request | No | Yes; a request to a public URL resumes a paused box | No; a stopped sandbox is started by API |
| Fork and snapshots | Snapshot the filesystem into an image; memory snapshots in alpha | Snapshot a running box and start many new boxes from it | Fork a running sandbox with its disk, without stopping it |
| Custom images | Build images in code or pull any linux/amd64 registry image | Custom images listed as coming soon; reuse setups through snapshots | Named snapshots used as templates; no Dockerfile builds |
| GPUs | T4 to B300; 10 at once on Starter, 50 on Team | None | None |
| Desktop, browser, computer use | Not offered; an example shows how to set up VNC yourself | Managed headless Chromium with AI page actions and CDP; no desktop | 60fps Linux desktop, Chromium and computer-use API built in |
| Coding agents | Examples only | Claude Code, Codex and OpenCode built in, with run and stream APIs, webhooks and scheduled prompts | Claude Code, Codex and others preinstalled, with a prompt, steer and events API |
| Keeping API keys out of the sandbox | Secrets are environment variables, or you run your own proxy in a sidecar | Host proxy injects headers into outbound HTTPS on port 443, set at creation | Credentials proxy for model providers and any HTTPS API; switch to another account when credits run out |
| Outbound network rules | Block all, IP-range allowlist, domain allowlist (beta) | Allow or deny by domain and CIDR, changeable on a running box | Open internet, no provider-side allowlist |
| Regions | US, EU and Asia-Pacific; pinning costs 1.15x to 1.75x | US only (AWS us-east-1) | EU only (Germany, Finland, France) |
Every feature Battleships tracks (43)
| Feature | Modal | Upstash Box | boat |
|---|---|---|---|
| Full VM (own kernel) | No | No | Yes |
| Docker inside | No | No | Yes |
| Nested virtualization | No | No | Yes |
| Root | Yes | Not published | Yes |
| Systemd | Yes | Not published | Yes |
| Desktop GUI | No | No | Yes |
| Browser | No | Yes | Yes |
| Computer-use API | No | No | Yes |
| SSH | Yes | Yes | Yes |
| Persistent disk | Yes | Yes | Yes |
| Pause/resume | No | Yes | Yes |
| Automatic snapshots | No | No | Yes |
| Fork/clone | Yes | Yes | Yes |
| Live fork (no pause) | No | 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 | Yes | No |
| Wake on request | No | Yes | No |
| HTTPS preview URLs | Yes | Yes | Yes |
| Raw TCP inbound | Yes | No | Yes |
| Public IPv4 | No | No | No |
| Egress allowlist | Yes | Yes | 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 | Yes | No | No |
| Windows | No | No | No |
| Arm64 | No | Yes | 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 | Not published | Yes |
| Usage per sandbox (API) | Not published | Yes | Yes |
| Audit logs | Yes | Not published | No |
| SSO | Yes | No | No |
| SOC 2 | Yes | Yes | No |
| HIPAA | Yes | No | No |
| EU data residency | Yes | No | Yes |
| Zero data retention | Not published | Not published | Yes |
Performance
In the hpc-sandbox-benchmarks Node.js build-and-test loop at 4 vCPU / 8 GB, run on 29 September 2026, boat finished 26.69 runs per second, Modal's default gVisor sandbox 12.79 and its VM runtime 15.54. Upstash Box has no result in that test, so there is no comparable measurement for it.
Node.js build-and-test loop at 4 vCPU / 8 GB, higher is better. Measured with the open hpc-sandbox-benchmarks suite. Modal measured on: Sandbox (gVisor), request = size, any region. Upstash Box 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 | Modal, a month | Upstash Box, 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 | $15 · Starter · with limits | $21 · Pay as You Go | $20 · $20/mo |
| One agent that never stops 4 vCPU / 8 GB, 50 GB disk, running 24/7 all month | $178 · Starter · with limits | $21 · Pay as You Go | $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 | $2,229 · Starter · with limits | $900 · Pay as You Go · 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 | $792 · Team | $306 · Pay as You Go | $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 | $3,193 · Team · with limits | $1,822 · Pay as You Go | $2,000 · $2000/mo · with limits |
Modal: Modal bills by the second for whichever is higher, the CPU and memory you request or what you use, and an idle sandbox pays until it is terminated. Starter is free with $30 of monthly credit, Team is $250 a month with $100 of credit, and pinning a region multiplies the price by 1.15x to 1.75x.
Upstash Box: A standard box is billed for the CPU it actually uses, at $0.10, $0.20 or $0.40 per active CPU hour for Small, Medium and Large, plus $0.10 per GB-month of storage, and RAM is free. A keep-alive box costs a flat $8, $16 or $32 a month whether it is busy or not.
Upstash Box: boat charges one hourly rate per machine size, by the second, only while the sandbox runs. Plans start at $20 a month and the whole fee becomes usage credit; a stopped sandbox costs nothing.
Limits in those scenarios
On Modal a sandbox lives at most 24 hours and its root disk is wiped when it ends, so the workday, always-on and fleet scenarios only keep files you put in a Volume. Neither Modal's default sandbox nor an Upstash box runs Docker inside, so the 50-agent fleet fits neither. Upstash does not publish its egress price, and its keep-alive pool is billed whether used or not. For 1,000 short jobs at once, Upstash fits, while boat queues the starts at 90 a minute.
| Scenario | Modal | Upstash Box | 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 |
| None that bite |
| 1,000 short jobs at once |
|
|
|
Which one should you use?
Use Modal when
your sandboxes need GPUs, must run outside the US, or are huge bursts of short jobs that finish well within a day.
- GPUs on the same platform. Useful if your agent trains or runs models: Modal rents GPUs from T4 to B300 next to its sandboxes.
- Regions around the world. Modal runs in the US, EU and Asia-Pacific, while Upstash Box runs only in AWS us-east-1.
- Huge fleets of short jobs. Useful for RL rollouts and big batches: Modal runs up to 5,000 containers on Team and builds images from any registry.
Use Upstash Box when
your agents mostly wait, need to wake on an incoming request, keep their files for days, and can run in the US without Docker.
- A box that waits for free. Good for agents that wait a lot: an idle box costs no CPU, RAM is not billed, and a request wakes it.
- Work that lasts past a day. A box keeps its files across pauses with no documented session cap, while a Modal sandbox ends within 24 hours.
- Coding agents built in. Claude Code, Codex and OpenCode come ready to run, with webhooks and scheduled prompts; on Modal you wire them up yourself.
Where boat fits
If what you are running is coding or computer-use agents that work for hours, both Modal and Upstash Box make you work around missing pieces. boat gives each agent a full VM with Docker, a desktop and a disk that stays, on a CPU that did about twice the work of Modal's default sandbox in the same benchmark.
Docker and /dev/kvm in every sandbox
Modal runs Docker only on its VM runtime, and nested virtualization only on request for Team and Enterprise. An Upstash box is itself a container with no Docker inside, so the 50-agent scenario fits neither.
A desktop the agent can see
Modal has no desktop, so you set up VNC yourself, and Upstash gives a headless Chromium only. boat streams a 60fps Linux desktop with computer-use tools, so the agent can open the app it built and check it.
A disk that keeps the work
A Modal sandbox ends within 24 hours and wipes everything outside a Volume. Upstash keeps files but caps disk at 10 GB on its 4 vCPU size. boat gives 50 GB, saved every minute, and stops cost nothing.
Use boat when your agents need a real machine: Docker, emulators, a desktop and a big disk that stays, on a fast CPU, for as long as the work takes. Compare it one to one: boat vs Modal and boat vs Upstash Box.
Questions people ask
Is Modal cheaper than Upstash Box?
In four of our five scenarios Upstash Box costs less: one agent that never stops is $21 a month against $178 on Modal, and sandboxes for your users are $306 against $792. Modal is cheaper for one agent on workdays ($15 against $21), but its files reset between days unless you use a Volume.
Which is faster, Modal or Upstash Box?
Only Modal has a result in the hpc-sandbox-benchmarks CPU test: 12.79 runs per second for its default sandbox and 15.54 for its VM runtime at 4 vCPU / 8 GB. Upstash Box has no comparable measurement. boat did 26.69 in the same run.
Can Modal or Upstash Box run Docker?
Modal runs Docker only on its VM runtime, chosen with runtime="vm". Upstash Box does not document it: each box is itself a Docker container. Every boat sandbox runs Docker and systemd with no extra setting.
How long can a sandbox run on Modal and Upstash Box?
A Modal sandbox defaults to 5 minutes and lasts at most 24 hours. An Upstash box has no documented cap: it pauses when idle and resumes later with its files, and a keep-alive box stays on all month. boat has no session cap on paid plans.
Do Modal or Upstash Box have GPUs?
Modal does, from T4 up to B300, on its default gVisor runtime. Upstash Box has none, and boat sandboxes are CPU machines too, so for GPU work Modal is the fit.
Where do Modal and Upstash Box run?
Modal runs in the US, the EU and Asia-Pacific, and you can pin a sandbox to a region for a higher price. Upstash Box runs in AWS us-east-1 only. boat runs in the EU, in Germany, Finland and France.
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