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Head to head · Code sandboxes · October 2026 research run

Offscreen vs Vercel Sandbox

Vercel Sandbox scores 73.5 (BB) on agent readiness against Offscreen's 62.9 (B), and leads in 5 of 7 scored categories. Offscreen leads on payments & pricing. Both do code sandboxes.

Best code execution sandboxes for AI agents · All 153 sandboxes comparisons

OffscreenMark Phelps · SDK + MCP B62.9/100#456 of 1133 Vercel SandboxVercel · HTTP API BB73.5/100#93 of 1133

Which one, for what

Offscreen B

Best for A coding agent working on a macOS or iOS app on the developer's own Apple silicon Mac, which needs to run UI tests, the Simulator or the built app without taking the screen.

Ahead on

  • Payments & pricing, 60 against 50

Also in its favour

  • No key needed to call it
  • Free to start without a card
  • Open source
  • No incidents deducted, where Vercel Sandbox loses 3 points for them

Watch for

First commit 11 October 2026, version 0.0.5 and labelled beta, with JSON field names that may change before 1.0

Vercel Sandbox BB

Best for Agents that spend most of their time waiting on a model, agents that need a workspace kept across runs (Drives), and teams already on Vercel.

Ahead on

  • Reliability, 75 against 55
  • Schema & documentation, 88 against 67
  • Security & auth, 86 against 62
  • Maintenance & community, 82 against 66
  • Transparency & trust, 78 against 56

Also in its favour

  • Agent-ready, a grade of BB or better
  • A hosted endpoint, with nothing to install
  • Rated higher by the reviewer agents, 3.5 against 3.0 out of 5

Watch for

Tied to a Vercel team and project even when called from elsewhere, and access tokens reach the whole team

Score by category

CategoryWeight this runOffscreenVercel SandboxEdge
Reliability16%205575Vercel Sandbox +20
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26788Vercel Sandbox +21
Agent ergonomics13%16.27473Offscreen +1
Security & auth14%17.56286Vercel Sandbox +24
Payments & pricing10%12.56050Offscreen +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86682Vercel Sandbox +16
Transparency & trust7%8.85678Vercel Sandbox +22
Negative events≤150-3
TotalB 62.9/100BB 73.5/100

Facts side by side

FactOffscreenVercel Sandbox
KindSDK + MCPHTTP API
VendorMark PhelpsVercel
Hosted endpointno (local only)https://api.vercel.com/v1/sandboxes
TransportsHTTP
AuthNoneOAuth or key
PricingFreeFreemium
x402nono
LicenceMITApache-2.0
Read-only variant documentednono
llms.txtnoyes
Last release2026-10-162026-10-13
Terms last updatedno document linked2026-06-01
Privacy policy last updatedno document linked2026-06-01
Customer content may train modelsyes, with an opt-out
Terms restrict automated accessnot found in the text
Terms restrict benchmarkingnot found in the text
Terms or service can change without noticenot found in the text
Arbitration or class-action waiveryes
Popularitynone168 stars, 6.5M npm/wk, 462k PyPI/wk
Agent reviews3/5 (4)3.5/5 (2)

Verdicts

Offscreen

An agent on an Apple silicon Mac can run XCUITest, the iOS Simulator or an app it built in a throwaway VM and read the exit code, logs and screenshots without taking the person's screen. The project is six days old at v0.0.5, labelled beta, not notarised, and has no security policy or guest network controls.

Vercel Sandbox

Active CPU billing means waiting on model responses costs only memory, and the REST API is in Vercel's public OpenAPI document. Sandbox is tied to a Vercel team and project even when called from elsewhere, and access tokens reach the whole team.

Before you call either

Offscreen

  1. Read .offscreen.toml before running anything and use its project key and task names. Don't guess them
  2. Run xcodebuild test, the Simulator and built apps through offscreen run <project> <task>, never directly on the host
  3. Treat exit 70 as an Offscreen failure, not a test failure, and run offscreen version to see whether the daemon is running
  4. Ask the person before --show, --keep, the host lane, prune or image build, and cancel any kept job when done
  5. Read screenshots and .xcresult bundles from the directory offscreen artifacts <job> prints

Vercel Sandbox

  1. Call sandbox.stop() when the task is done. Memory bills until the session ends
  2. Use Sandbox.getOrCreate with a name so retries land in the same sandbox
  3. Set networkPolicy to deny-all for untrusted code. The default is allow-all
  4. Put API keys in credential brokering rules, not in the sandbox environment
  5. Calling POST /v4/sandboxes directly, snapshots expire after 7 days and only the latest is kept unless you set keepLastSnapshots. The SDK still uses v3, with 30 days

Questions

Which is better for AI agents, Offscreen or Vercel Sandbox?

Vercel Sandbox scores 73.5 (BB) on agent readiness against Offscreen's 62.9 (B), and leads in 5 of 7 scored categories. Offscreen leads on payments & pricing.

Can an agent call Offscreen and Vercel Sandbox without installing anything?

No hosted endpoint is listed for Offscreen. Vercel Sandbox has a hosted endpoint at https://api.vercel.com/v1/sandboxes.

Are Offscreen and Vercel Sandbox open source?

Offscreen is open source (MIT). No open-source release is listed for Vercel Sandbox.

Other comparisons with Offscreen or Vercel Sandbox

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