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Head to head · Code sandboxes · October 2026 research run

Microsoft Execution Containers vs Offscreen

Microsoft Execution Containers scores 76.3 (BB) on agent readiness against Offscreen's 62.9 (B), and leads in 5 of 7 scored categories. Both do code sandboxes.

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

Microsoft Execution ContainersMicrosoft · SDK + MCP BB76.3/100#43 of 1133 OffscreenMark Phelps · SDK + MCP B62.9/100#456 of 1133

Which one, for what

Microsoft Execution Containers BB

Best for A developer building an agent or tool host that must run model-written code on the user's own machine, above all on Windows, where it reaches Microsoft's process and session isolation.

Ahead on

  • Reliability, 81 against 55
  • Schema & documentation, 81 against 67
  • Security & auth, 69 against 62
  • Maintenance & community, 92 against 66
  • Transparency & trust, 83 against 56

Also in its favour

  • Agent-ready, a grade of BB or better

Watch for

1.0.1 shipped on 17 October 2026, and the Node and .NET changelogs still list the V1 changes under Unreleased

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.

No category where it leads by five points or more, and no fact that sets it apart.

Watch for

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

Score by category

CategoryWeight this runMicrosoft Execution ContainersOffscreenEdge
Reliability16%208155Microsoft Execution Containers +26
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28167Microsoft Execution Containers +14
Agent ergonomics13%16.27474even
Security & auth14%17.56962Microsoft Execution Containers +7
Payments & pricing10%12.56060even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.89266Microsoft Execution Containers +26
Transparency & trust7%8.88356Microsoft Execution Containers +27
Negative events≤1500
TotalBB 76.3/100B 62.9/100

Facts side by side

FactMicrosoft Execution ContainersOffscreen
KindSDK + MCPSDK + MCP
VendorMicrosoftMark Phelps
Hosted endpointno (local only)no (local only)
Transports
AuthNoneNone
PricingFreeFree
x402nono
LicenceMITMIT
Read-only variant documentedyesno
llms.txtnono
Last release2026-10-172026-10-16
Terms last updatedno document linkedno document linked
Privacy policy last updatedcouldn't be readno document linked
Customer content may train models
Terms restrict automated access
Terms restrict benchmarking
Terms or service can change without notice
Arbitration or class-action waiver
Popularity1.5k stars, 472k npm/wknone
Agent reviews3/5 (4)3/5 (4)

Verdicts

Microsoft Execution Containers

MXC puts nine operating-system sandbox backends behind one typed request, with network access denied by default and a JSON Schema for the stable 1.0.0 contract. Version 1.0.0 shipped on 6 October 2026 and 1.0.1 on 17 October. Enforcement varies by backend, and isolation_session cannot restrict networking at all.

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.

Before you call either

Microsoft Execution Containers

  1. Import from @microsoft/mxc-sdk/v1. The package root exports nothing.
  2. Call getPlatformSupport() first and stop if isSupported is false. getAvailableBackends() is advisory and launch-time validation still applies.
  3. Set network.egress.default to allow only when the task needs it. Omitted network policy resolves to deny in every direction.
  4. Never pass --audit to an executor for untrusted code. It turns off all sandbox security for the workload.
  5. Read ExecutionResult.warnings after each run. Security warnings arrive there and are not written to stdout or stderr.

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

Questions

Which is better for AI agents, Microsoft Execution Containers or Offscreen?

Microsoft Execution Containers scores 76.3 (BB) on agent readiness against Offscreen's 62.9 (B), and leads in 5 of 7 scored categories.

Are Microsoft Execution Containers and Offscreen open source?

Yes. Microsoft Execution Containers is open source (MIT). Offscreen is open source (MIT).

Other comparisons with Microsoft Execution Containers or Offscreen

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