E2B vs Fly Machines
Comparing architecture, runtime limits, open-source licenses, and monthly costs for autonomous agent pipelines.
Detailed Specifications & Compatibility Matrix
Extracted directly from GitHub REST API & official developer documentation
| Technical Feature / Metric | E2B | Fly Machines |
|---|---|---|
| Developer / Organization | E2B Labs Inc. (Vasek Mlejnsky & Martin Soucek) | Fly.io Inc. (Kurt Mackey & Team) |
| Open-Source Engine | ✓ Open Source (Apache-2.0) | ✓ Open Source (Apache-2.0) |
| GitHub Stars (Repo/SDK) | ★ 14,548 GitHub Stars | ★ 1,719 GitHub Stars |
| Core Repository Language | Python | Go |
| Supported SDK Clients | ||
| Self-Hosted Deployment | ✓ Supported | Hosted Only |
| Docker / Container Ready | ✓ Official Image | ✓ Official Image |
| Model Context Protocol (MCP) | ✓ Native MCP | Standard REST/gRPC |
| Billing Architecture | usage based | usage based |
| Developer Free Tier | ✓ Yes 100 hours of sandbox microVM runtime / mo | ✓ Yes 3 shared-cpu-1x microVMs allowance |
| Entry Paid Tier (Monthly) | Free / Custom | $1.94 USD / mo |
| Pricing & Cost Architecture | Developer free tier provides $100 in trial compute credits. Standard compute is metered per second, starting at ~$0.05/hour per active vCPU with zero idle sandbox costs. | Pay-as-you-go billed per second: shared CPU microVMs start at ~$0.0000022/second (~$1.94/month if running 24/7). Stopped machines pay only for attached NVMe disk storage ($0.15/GB/mo). |
| Key Engineering Insight | Built on AWS Firecracker (the microVM technology powering AWS Lambda); boots isolated Linux environments in under 150 milliseconds to safely execute untrusted AI-generated code. | Operates custom bare-metal servers across 35+ global edge datacenters, booting Linux kernels directly on KVM without container orchestration overhead. |
Strengths & Trade-Offs
Objective engineering evaluation of both platforms
E2B Evaluation
Key Advantages
- ✓ Hardware-isolated microVMs powered by AWS Firecracker with sub-150ms cold start initialization
- ✓ Custom sandbox templates allowing developers to pre-install specific system packages, Python wheels, and binaries
- ✓ Official SDKs for Python and TypeScript with native stdout/stderr streaming and artifact file downloads
Limitations & Trade-Offs
- ✕ Maximum continuous session execution duration capped at 24 hours per persistent sandbox instance
- ✕ Requires configuring custom egress firewall rules if sandboxes need to access private local enterprise APIs
Fly Machines Evaluation
Key Advantages
- ✓ Sub-300ms boot times for custom Docker images running in 35+ global edge data centers close to end users
- ✓ Full persistent NVMe volume support with customizable memory/vCPU ratios per individual machine instance
- ✓ Fast REST API allowing agents to dynamically spawn, pause, snapshot, and destroy microVMs programmatically
Limitations & Trade-Offs
- ✕ Requires managing base Linux Docker images, security firewall configurations, and internal WireGuard routing
- ✕ Lacks a specialized high-level code execution SDK out of the box (requires building custom API wrappers)
Source Quotes
Direct excerpts from official documentation backing our extracted specifications
E2B Documentation Proof
"Billed per second of actual sandbox compute from $0.05 per active vCPU hour."
"Includes 100 hours of free sandbox runtime every month."
"Core SDKs and template definitions open source on GitHub."
Fly Machines Documentation Proof
"Shared CPU instances start at $0.0000022/second (~$1.94/mo)."
"Free resource allowances include up to 3 shared-cpu-1x microVMs."
"Global microVM platform running on Fly.io bare metal hardware."
Frequently Asked Questions: E2B vs Fly Machines
Architectural trade-offs and decision criteria
Is E2B or Fly Machines cheaper for developers?
E2B has a starting price of $0/mo (usage based), while Fly Machines starts at $1.94/mo (usage based). E2B includes a free tier (100 hours of sandbox microVM runtime / mo). Fly Machines offers a free tier (3 shared-cpu-1x microVMs allowance).
Can I self-host E2B and Fly Machines in my own infrastructure?
E2B is self-hostable under the Apache-2.0 license. In comparison, Fly Machines is proprietary cloud infrastructure.
Do E2B and Fly Machines support the Model Context Protocol (MCP)?
E2B has native support for MCP servers. Fly Machines does not advertise built-in MCP protocol bindings.
Which programming languages have official SDKs for E2B vs Fly Machines?
E2B provides official SDKs in: python, typescript. Meanwhile, Fly Machines supports: go, curl, python.