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Status notice

Deno Sandbox (winding down)

Answer in brief

Deno Sandbox is no longer included in Deno Deploy plans and is not available to new customers as of November 2026, following the announcement that Deno is joining Cloudflare. Closest alternatives: Cloudflare Sandbox SDK, Vercel Sandbox, E2B.

By the Agent Sandboxes editors · Updated

Status: Deno Sandbox is no longer included in Deno Deploy plans and is not available to new customers as of November 2026, following the announcement that Deno is joining Cloudflare.

Overview

Deno Sandbox is an SDK and API for starting Linux microVMs on Deno Deploy, aimed at running agent-generated or untrusted code. Each sandbox has 2 vCPUs, 768 MB-4 GB of memory and 10 GB of ephemeral disk, boots from a clean image and is torn down when the last reference is dropped or its timeout expires. The distinctive features are an outbound proxy that enforces allowNet host allow-lists and a secrets mechanism in which code only ever sees a placeholder, with the real value substituted on requests to approved hosts, as a defence against prompt-injection exfiltration. There are JavaScript (@deno/sandbox) and Python (deno-sandbox) SDKs, a deno sandbox CLI and a REST API.

Persistence comes from read-write volumes and read-only snapshots rather than from pausing a VM; volumes are limited to the Chicago region. The product launched in beta on 3 February 2026 with per-hour CPU and per-GB-hour memory pricing, and the docs still describe a "pre-release phase" with a default of 5 concurrent sandboxes per organisation. In November 2026, as Deno announced it was joining Cloudflare, the launch post gained a note that Deno Sandbox is no longer included in Deno Deploy plans and is not available to new customers, so this record documents a product that existing customers may still use but that newcomers cannot sign up for.

Notable

  • Launched in beta on 3 February 2026
  • Note dated November 2026 on the launch post: no longer included in Deno Deploy plans and not available to new customers, alongside the announcement that Deno is joining Cloudflare
  • Default concurrency of 5 sandboxes per organisation during the pre-release phase

Deno Sandbox specifications

AttributeDetails
IsolationLinux microVM per sandbox, "isolated at the hypervisor level"; product page says Firecracker, the security docs do not name the hypervisor
DeploymentHosted platform
Open sourceNo
SDKs and interfacesJavaScript/TypeScript, Python, CLI, REST API
Cold start (vendor claim)Product page FAQ: "Under 200ms"; launch post: boot time under 1 second (vendor claims)
Max session lengthSession-bound by default; a duration timeout keeps it alive after disconnect and can be extended, with the About page and launch post giving a 30-minute lifetime cap (extendable on demand); longer-lived work is meant to be promoted to a Deno Deploy app
PersistenceVMs are ephemeral and boot from a clean image; read-write volumes (300 MB-20 GB, one sandbox at a time, Chicago region only) survive sandbox teardown, and read-only snapshots of a volume can be used as the root filesystem for many sandboxes at once; no pause/resume of a running VM
GPUNo - not mentioned anywhere in the docs or product page
NetworkingOutbound goes through a proxy enforcing allowNet host patterns (exact hosts, ports, wildcard subdomains, IPs); the security page says outbound is unrestricted by default while the create page says the default is no outbound access; secrets are placeholders inside the VM and substituted only on requests to approved hosts; HTTP, SSH and VS Code can be exposed
PricingLaunch post: CPU time $0.05/hour, memory $0.016/GB-hour, volume storage $0.20/GiB-month, with 40 CPU-hours, 1,000 GB-hours and 5 GiB included on the $20/month Pro plan; the same post carries a note dated November 2026 that Deno Sandbox "is no longer included in Deno Deploy plans and is not available to new customers"
Free tierFree Deno Deploy plans were stopped at their usage limits rather than billed; not available to new customers as of November 2026
ComplianceNot documented
RegionsAmsterdam (ams) and Chicago (ord); volumes only in Chicago

Facts from Deno Sandbox’s public documentation, verified November 9, 2026. Performance numbers are vendor claims.

Strengths and trade-offs

Strengths

  • You are an existing Deno Deploy customer who wants microVM code execution inside the same platform
  • You need egress allow-lists and secrets that never enter the sandbox environment
  • You want to promote a sandbox into a deployed Deno Deploy app with one call

Trade-offs

  • Not available to new customers as of November 2026
  • Lifetime capped at 30 minutes per the About page, with no pause/resume of a running VM
  • Fixed 2 vCPUs and at most 4 GB memory; volumes only in the Chicago region
  • Pre-release default of 5 concurrent sandboxes per organisation

Good fit for: Short, bursty untrusted-code runs by existing Deno Deploy customers who need egress allow-lists and proxy-injected secrets.

How Deno Sandbox compares

SandboxIsolationOpen sourceSelf-host / BYOCCold start (vendor)Max sessionSnapshots / pauseGPUSDKs
Deno SandboxFirecracker microVMNoNo / No<200 ms (claim)30 min (extendable)Yes / NoNoJavaScript/TypeScript, Python, CLI, REST API
Cloudflare Sandbox SDKMicroVM (Containers)YesNo / No1–3 sNo fixed capYes / Not documentedNot documentedTypeScript (Workers)
Vercel SandboxFirecracker microVMNoNo / NoMilliseconds (claim)24 h (Pro)Yes / YesNot documentedJavaScript/TypeScript, Python
E2BFirecracker microVMYesYes / YesNot documented1 h / 24 h (Pro)Yes / YesNoPython, JavaScript/TypeScript
HopXFirecracker microVMNoNo / No~100 ms (claim)No capNot documented / YesNot documentedPython, JavaScript/TypeScript, CLI, REST API, MCP server
Fly.io SpritesMicroVMNoNo / No0.1–2 s wakeUnlimitedYes / YesNoJavaScript/TypeScript, Go, Python, Elixir

See all Deno Sandbox alternatives →

Frequently asked questions

What is Deno Sandbox?
Linux microVMs on Deno Deploy with host allow-lists and proxy-injected secrets; launched in beta in February 2026 and, as of November 2026, no longer available to new customers. A well-designed microVM sandbox with strong egress and secret controls, but one that is closed to new customers following the Cloudflare announcement.
How does Deno Sandbox isolate code?
Deno Sandbox documents its isolation as: Linux microVM per sandbox, "isolated at the hypervisor level"; product page says Firecracker, the security docs do not name the hypervisor.
Is Deno Sandbox open source?
No, Deno Sandbox is not open source.
How much does Deno Sandbox cost?
Launch post: CPU time $0.05/hour, memory $0.016/GB-hour, volume storage $0.20/GiB-month, with 40 CPU-hours, 1,000 GB-hours and 5 GiB included on the $20/month Pro plan; the same post carries a note dated November 2026 that Deno Sandbox "is no longer included in Deno Deploy plans and is not available to new customers" Check the official pricing page for current rates.
What are the alternatives to Deno Sandbox?
Common alternatives include Cloudflare Sandbox SDK, Vercel Sandbox, E2B, HopX, Fly.io Sprites. See Deno Sandbox alternatives for a full comparison.

Sources

  1. deno.com/deploy/sandbox
  2. docs.deno.com/sandbox/
  3. docs.deno.com/sandbox/security/
  4. docs.deno.com/sandbox/create/
  5. docs.deno.com/sandbox/timeouts/
  6. docs.deno.com/sandbox/volumes/
  7. deno.com/blog/introducing-deno-sandbox
  8. deno.com/deploy/pricing
  9. github.com/denoland/sandbox-py

Cite this page

Agent Sandboxes. (2026). Deno Sandbox (winding down). agentsandboxes.org. Last reviewed November 9, 2026. https://agentsandboxes.org/sandboxes/deno-sandbox/

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