#99th of 20 in App builder starters
runtime
Firecracker microVM sandbox backend for running untrusted AI agent code
- Stars
- 1.8k
- License
- Apache-2.0
- Last commit
- Nov 2026
- Last release
- Sep 2026
- Language
- Go
1,031 on 21 Apr 20261,834 on 10 Nov 2026
From GitHub's daily star counts.
Checked on GitHub.
E2B is hiring: 14 open roles
Overview
Go backend behind E2B Cloud: a REST API, a per-node orchestrator that drives Firecracker, an in-VM agent (envd), an edge proxy and a template builder. Each sandbox is a microVM restored from a snapshot with lazy memory paging, and it can be paused, resumed or forked. A single-host Embed package runs the stack on a Linux machine with KVM.
Who it is for: Platform and infra engineers self-hosting sandboxes for AI agent code execution
Ranked among open-source alternatives to Bolt.new (#9 of 10) and Replit (#9 of 10).
Strengths
- Hardware isolation per sandbox: own microVM, cgroup, network namespace and nftables egress rules
- Pause, resume and fork of live sandboxes, with up to 100 forks per request
- Templates built from Docker images with hashed, cached layers
- Single-host Embed package, plus Terraform for GCP, AWS and Azure and a Kubernetes manifest
Weaknesses
- Requires a Linux host with KVM; no macOS or Windows host support
- Needs PostgreSQL, Redis, ClickHouse and object storage, so it is heavy to operate
- Embed is limited to one machine; multi-node production is a paid enterprise deployment
- Architecture is complex; the README tells readers to study the architecture doc first
What it needs
- Go
- Needs Linux with KVM, Firecracker, PostgreSQL, Redis, ClickHouse, Object storage, Docker Compose (Embed)
Quick answers
Is runtime open source?
Yes. Its code is on GitHub under the Apache-2.0 license.
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