E2B vs Microsoft Execution Containers

E2B

Firecracker microVM with its own kernel per sandbox. Two major incidents over an hour in September 2026, on sandbox creation and on creating from snapshots.

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 is two days old as of 8 October 2026. Enforcement varies by backend, and isolation_session cannot restrict networking at all.

E2B

1. Set a timeout when you create a sandbox. The default is 5 minutes
2. Pause rather than kill when you'll come back. Resume takes about a second and nothing is billed while paused
3. Use Secret.fill in network transforms instead of passing API keys into the sandbox environment
4. Pace sandbox creation. Hobby allows 1 a second and 20 running at once
5. Move to the v2 sandbox endpoints. SDK 2.51.0 and later use them by default

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.