Replit vs Deno Sandbox
Replit is an AI app builder: you describe an app, Replit Agent writes it, and Replit hosts it. Deno Sandbox is an API that runs short pieces of untrusted code in 2 vCPU Firecracker microVMs that start in under 200 ms and live up to 30 minutes.
The companies and products
Replit
Replit is an AI app builder and hosting platform: you describe an app in chat, Replit Agent writes it, and Replit publishes it.
You work in a browser workspace where Replit Agent sets up the project, writes the code, tests it and fixes problems, with system packages managed by Nix. When the app is ready you publish it as an Autoscale, Static, Scheduled or Reserved VM deployment, with Postgres and object storage next to it. It is built for people and teams who want a working app, not for programs that need to create many machines by API, so this page compares the parts where the two overlap.
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. “181st cheapest of 367” means 180 of the other 366 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 | Replit: 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 A software factory runs installs, builds and Docker for hours: Deno stops at 30 minutes on 2 vCPU, Replit drives only its own agent one app at a time, and boat gives each agent a full VM. | 181st of 367, with limits $2,000 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 fits a Replit Reserved VM better than a Deno sandbox that ends after 30 minutes, and on boat it can also stop and keep its disk. | 202nd of 366, with limits $2,033 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 Short code runs suit Deno Sandbox best of the two: it starts in under 200 ms and bills CPU only while code runs, while Replit is a web host, not a code runner. | 228th of 345, with limits $146 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 Deno gives each user a locked-down sandbox but caps Builder at 20 at once per region, Replit does not publish how many deployments can run at once, and boat's plans go to hundreds. | 233rd of 361, with limits $825 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 | 258th of 360, with limits $4,226 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 | 265th of 364, with limits $685 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 containers or boot emulators need Docker and /dev/kvm, which neither Replit nor Deno documents and every boat sandbox has. | 275th of 377, with limits $425 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 Replit workspace is a good place to code by hand and a Deno sandbox is gone after 30 minutes; a boat dev box stays on with Docker, systemd and a disk that persists. | 165th of 368, with limits $109 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 Replit's VNC pane shows a desktop to a person, Deno Sandbox has no desktop, and boat streams a Linux desktop at 60fps with Chromium and a computer-use API. | 190th of 369, with limits $619 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 | 229th of 367, with limits $317 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 | 234th of 346, with limits $217 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 | 150th of 338, with limits $4,378 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 | 208th of 360, with limits $215 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 | Replit | Deno Sandbox | boat |
|---|---|---|---|
| Kind of product | AI app builder with browser workspaces and app hosting | Sandbox API for short runs of untrusted or AI-generated code, part of Deno Deploy | Sandboxes you create, stop and fork by API, SDK or CLI |
| Isolation | Not documented; the security page says strong logical separation between users | Firecracker microVM with its own kernel | Full VM with its own kernel on dedicated AMD Ryzen 9 9950X hosts |
| Creating machines from code | MCP server tools to create, update and publish apps; no API to start many machines | TypeScript or Python SDK to create sandboxes | API, SDK and CLI to create, stop, resume and fork many sandboxes |
| Machine size | Reserved VM sizes such as dedicated 4 vCPU / 16 GB; workspace sizes no longer published | 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 |
| How long a machine runs | A Reserved VM runs continuously and bills all month | Up to 30 minutes; longer work can be promoted to a Deno Deploy app | No cap on paid plans; stopping a sandbox ends the bill |
| Files over time | Workspace files and Agent checkpoints; published apps should not rely on their filesystem | Root disk wiped when the sandbox ends; opt-in volumes of 300 MB to 20 GB, Chicago only | Whole disk kept, saved every minute and on stop; a stopped sandbox costs nothing |
| Docker and nested virtualization | System packages come from Nix; Docker, systemd and /dev/kvm not documented | Root access; Docker and nested virtualization not documented | Docker, root, systemd and /dev/kvm on every machine |
| Coding agents | Replit Agent, which an MCP client can drive (create, update, ask, publish) | A root image with Claude Code, run through the shell command API | Seven agents preinstalled, including Claude Code and Codex, with a prompt, steer and events API |
| Desktop and computer use | VNC pane that streams a native desktop to your browser; no computer-use API | No desktop; a VS Code editor in the browser and SSH | Linux desktop streamed at 60fps, Chromium and computer use built in |
| Outbound traffic and keys | Replit manages keys for OpenAI, Anthropic, Google and OpenRouter models; other keys are secrets in the app | Host allowlist per sandbox, and placeholder secrets swapped for real ones at a proxy outside the VM | Open internet; credentials proxy for model providers and any HTTPS API, with a switch to another account when credits run out |
| Reaching the machine | Published apps on HTTPS domains, custom domains and private deployments; SSH into the workspace on paid plans | HTTPS URL per exposed port, public without authentication; SSH | HTTPS URLs for up to 50 ports, token-protected by default; raw TCP; SSH |
| Start time | Autoscale apps start on the first request; start time not published | Under 200 ms | Boots a full VM |
| Hosting finished apps | Autoscale, Static, Scheduled and Reserved VM deployments, with Postgres and App Storage; Autoscale costs nothing while idle | A sandbox can be promoted to a Deno Deploy app | No hosted databases or wake on request; you stop and resume sandboxes yourself |
| Regions | Published apps in North America, Europe, Asia, South America and Australia on Core and up | Amsterdam and Chicago; volumes only in Chicago | EU only: Germany, Finland, France |
Every feature Battleships tracks (43)
| Feature | Replit | Deno Sandbox | boat |
|---|---|---|---|
| Full VM (own kernel) | Yes | Yes | Yes |
| Docker inside | No | Not published | Yes |
| Nested virtualization | No | No | Yes |
| Root | Not published | Yes | Yes |
| Systemd | No | Not published | Yes |
| Desktop GUI | Yes | No | Yes |
| Browser | No | No | Yes |
| Computer-use API | No | No | Yes |
| SSH | Yes | Yes | Yes |
| Persistent disk | Yes | Yes | Yes |
| Pause/resume | No | No | Yes |
| Automatic snapshots | Yes | No | Yes |
| Fork/clone | Yes | No | Yes |
| Live fork (no pause) | No | No | Yes |
| Memory fork | No | 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 | Not published | No | Yes |
| Public IPv4 | No | No | No |
| Egress allowlist | No | Yes | No |
| Secret proxy | Yes | Yes | Yes |
| Secret proxy for any API | No | Yes | Yes |
| Preinstalled agents | Yes | Yes | Yes |
| Agent harness API | Yes | No | Yes |
| MCP server | Yes | No | No |
| GPU | No | No | No |
| Windows | No | No | No |
| Arm64 | Not published | 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 | Yes | Yes | Yes |
| Usage per sandbox (API) | Yes | No | Yes |
| Audit logs | Yes | Not published | No |
| SSO | Yes | No | No |
| SOC 2 | Yes | Yes | No |
| HIPAA | No | Yes | No |
| EU data residency | Yes | Yes | Yes |
| Zero data retention | Not published | Not published | Yes |
Performance
There is no comparable measurement for Replit or Deno Sandbox: neither is in StarSling's public hpc-sandbox-benchmarks, and Deno's fixed 2 vCPU shape could not run its 4 vCPU test as set up. boat did 26.69 Node.js build-and-test runs per second at 4 vCPU / 8 GB in that benchmark. Deno says a sandbox starts in under 200 ms; Replit publishes no start time.
Node.js build-and-test loop at 4 vCPU / 8 GB, higher is better. Measured with the open hpc-sandbox-benchmarks suite. Replit 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 | Replit, 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 | $122 · Pro $100 (annual) · with limits | $53 · Pro · with limits | $20 · $20/mo |
| One agent that never stops 4 vCPU / 8 GB, 50 GB disk, running 24/7 all month | $122 · Pro $100 (annual) · with limits | $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 | $1,330 · Pro $1,000 (annual) · with limits | $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 | $403 · Pro $250 (annual) · 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 | $825 · Pro $1,000 (annual) · with limits | $1,563 · Builder · with limits | $2,000 · $2000/mo · with limits |
Replit: Replit plans (Core $20, Pro from $100) turn into monthly credits that pay for Agent work and hosting, then usage goes on to pay-as-you-go. A Reserved VM has a fixed monthly price per size, such as $130 for 4 vCPU / 16 GB, and bills whether busy or idle; Autoscale bills only while it serves requests.
Deno Sandbox: Sandboxes need the Pro plan 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 costs $0.10 per hour of active CPU time 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 becomes usage credit spent per second on running sandboxes. A stopped sandbox costs nothing and keeps its disk.
Limits in those scenarios
Neither Replit nor Deno Sandbox fits any of the five scenarios as written. Replit is an app platform: each always-on machine is a published Reserved VM that bills all month, and it does not publish how many deployments can run at once. Deno Sandbox ends each sandbox after 30 minutes, is fixed at 2 vCPU with up to 4 GB, and Builder allows 20 at once per region. boat fits four of the five; at 1,000 short jobs at once it queues starts above 90 a minute and needs more starts a day than its $2,000 plan allows.
| Scenario | Replit | 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 Replit when
you want Replit Agent to build a web app from a description and host it for you, with databases, sleeping when idle and regions on five continents.
- An app built and hosted for you. Useful if you want a working app from a description: Replit Agent builds, tests and publishes it with a domain, Postgres and storage.
- Hosting that costs nothing when idle. Useful for web apps with uneven traffic: Autoscale wakes on the first request and costs nothing while idle.
- Regions on five continents. Useful if your users are spread out: Replit publishes apps in North America, Europe, Asia, South America and Australia.
Use Deno Sandbox when
your code runs short pieces of untrusted code that must start in milliseconds and reach only the hosts you allow, especially if you already deploy on Deno Deploy.
- Locked-down outbound traffic. Useful for running untrusted code: each sandbox can be limited to a list of hosts, enforced by a proxy outside the VM.
- Fast starts and active-CPU billing. Good for short bursts of code: a sandbox starts in under 200 ms and CPU bills only while code runs.
- A sandbox API with a path to Deno Deploy. Fits teams already on Deno Deploy: your code creates sandboxes by SDK and can promote one to a Deploy app.
Where boat fits
Replit builds and hosts apps for people, and Deno Sandbox runs short pieces of code for up to 30 minutes. If what you are really running is coding agents that install, build and test for hours, look at boat: your code starts full VMs with Docker, a desktop and agents built in, and each one keeps its disk.
A machine that stays and keeps its files
A Deno sandbox ends after 30 minutes and wipes its root disk unless you mount a Chicago-only volume. A Replit Reserved VM stays up but bills all month. boat saves the whole disk every minute, and a stopped sandbox costs nothing.
Docker, systemd and /dev/kvm on a bigger machine
Neither Replit nor Deno documents Docker or nested virtualization, and Deno is fixed at 2 vCPU with up to 4 GB. An agent running docker compose or an Android emulator has nowhere to go; boat gives it up to 16 vCPU / 32 GB.
Agents driven from outside, with a desktop
Replit's MCP server drives only Replit Agent, with no event stream, and on Deno you run Claude Code through shell commands and parse its output. Neither has a computer-use desktop. boat has a prompt, steer and events API and a 60fps desktop.
Use boat when your agents do real work for more than a few minutes: installs, builds, Docker, emulators and a browser, on a full VM your code starts and whose disk is still there tomorrow. Compare it one to one: boat vs Replit and boat vs Deno Sandbox.
Questions people ask
Is Replit cheaper than Deno Sandbox?
In most scenarios we priced, yes: one agent that never stops comes to $122 on Replit against $200 on Deno Builder, and 50 agents in parallel to $1,330 against $2,779. Neither fits any scenario as written. On boat the same two come to $26 and $317 a month.
Which is faster, Replit or Deno Sandbox?
We cannot say: neither is in the public CPU benchmark we use, where boat did 26.69 runs per second at 4 vCPU / 8 GB. Deno says a sandbox starts in under 200 ms, and Replit does not publish a start time.
Can Replit or Deno Sandbox run Docker?
Neither documents it. Replit sets up environments with Nix packages, and Deno's docs give root access but do not mention Docker or nested virtualization. Every boat sandbox has Docker, systemd and /dev/kvm.
How long can a machine run on each?
A Deno sandbox lives up to 30 minutes and its root disk is wiped when it ends, unless the work is promoted to a Deno Deploy app. A Replit Reserved VM runs continuously and bills all month. A boat sandbox has no cap on paid plans and costs nothing while stopped.
Can I drive coding agents from my own code?
Partly. Replit's MCP server lets a client create and update apps through Replit Agent only, and Deno ships Claude Code in an image you run through shell commands. boat preinstalls seven agents and lets you prompt, steer and stream events from each through one API.
Where do Replit and Deno Sandbox run?
Replit hosts data mainly on Google Cloud in the United States and publishes apps in North America, Europe, Asia, South America or Australia on Core and up. Deno Sandbox runs in Amsterdam and Chicago. boat runs only in the EU, in Germany, Finland and France.
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