E2B
microvmcloud-platformopen sourceA sandbox platform that runs code in Firecracker , with per-sandbox network isolation, self-hostable or hosted.
E2B provides sandboxes for running AI-generated and untrusted code, built on Firecracker (KVM, own kernel), the strongest boundary among the common sandbox-infra platforms. Each sandbox gets its own subnet with a NAT allowlist for . It is Apache-2.0 and self-hostable (needing nested virtualization) as well as available hosted, and it advertises a middle path between the two: bring-your-own-cloud into your own AWS, GCP, or Azure account, plus on-prem and self-hosted VPC deployments. E2B advertises sub-200ms sandbox starts in-region, 80ms with no cold starts on its premium tier, and sandbox lifetimes up to 24 hours on Pro; those are vendor figures, not measured here. It is the infrastructure many agent products rent their isolation from.
Strengths
- Firecracker microVMs, a hardware boundary, the strongest common infra tier
- Joint-smallest host attack surface measured in the June 2026 study: 128 /dev entries behind a 55-syscall seccomp ceiling
- Zero information leakage across that study's 28 probes, tied best in the set
- Per-sandbox subnet with NAT egress allowlist
- Apache-2.0 and self-hostable, as well as hosted
- Bring-your-own-cloud (AWS/GCP/Azure), on-prem, and VPC deployments, so the boundary can sit inside your own account
Limitations
- Self-hosting needs nested virtualization
- Cloud/infra platform, not a local dev tool
- You still own egress policy and mount scoping for the workloads inside
- Pins its engine with no automated bump policy: as of June 2026 the self-hosted orchestrator default sat at Firecracker v1.14.1, pinned 2025-04-17 and unbumped for 399 days, leaving CVE-2026-5747 (escape-class, CVSS 8.7, OOB write in virtio-pci) unpatched for 44+ days after the upstream fix shipped. Check the pin yourself before adopting; it is a product policy, not an engine defect
- Firecracker has no documented upstream fuzzing infrastructure, so its low published-CVE count rests on less automated search than gVisor's
- Sandboxes are not indefinite, the advertised ceiling is 24 hours of continuous runtime on Pro
Files & editor
edit-insideProgrammatic microVM sandboxes driven from your code, not an interactive editor target.
How you get your project into the environment and edit it. Shared-kernel routes bind-mount host files for your desktop editor; own-kernel routes keep files in the guest, so a desktop editor attaches over remote, or you edit inside. Mounts and remote editing.