CodeSandbox API 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 | CodeSandbox API | Fly Machines |
|---|---|---|
| Developer / Organization | CodeSandbox B.V. (Ives van Hoorne & Bas Courbois) | Fly.io Inc. (Kurt Mackey & Team) |
| Open-Source Engine | ✓ Open Source (Apache-2.0) | ✓ Open Source (Apache-2.0) |
| GitHub Stars (Repo/SDK) | ★ 6,255 GitHub Stars | ★ 1,719 GitHub Stars |
| Core Repository Language | TypeScript | Go |
| Supported SDK Clients | ||
| Self-Hosted Deployment | Hosted Only | Hosted Only |
| Docker / Container Ready | ✓ Official Image | ✓ Official Image |
| Model Context Protocol (MCP) | Standard REST/gRPC | Standard REST/gRPC |
| Billing Architecture | flat fee | usage based |
| Developer Free Tier | ✓ Yes Free public sandboxes with session timeouts | ✓ Yes 3 shared-cpu-1x microVMs allowance |
| Entry Paid Tier (Monthly) | $18 USD / mo | $1.94 USD / mo |
| Pricing & Cost Architecture | Free tier includes public sandboxes with basic compute resources. Pro plan starts at $18/mo per user with private sandboxes, 6GB+ RAM, and persistent workspaces. | 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 | Pioneered in-browser and cloud microVM development environments; their architecture can snapshot a running Linux kernel memory state and resume it in under 500 milliseconds. | 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
CodeSandbox API Evaluation
Key Advantages
- ✓ Runs complete fullstack development servers (Next.js, Vite, Node, Python) with instant public HTTP port forwarding
- ✓ Instant memory branching: snapshot running application states in milliseconds without cold start penalties
- ✓ Seamless live preview URLs allowing AI agents to visually render and test interactive web interfaces
Limitations & Trade-Offs
- ✕ Proprietary cloud platform without an on-premise self-hosted edition
- ✕ Billed primarily on a monthly per-seat subscription model rather than sub-second micro-metering
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
CodeSandbox API Documentation Proof
"Pro subscription begins at $18/month per seat."
"Free public sandboxes with standard CPU and RAM limits."
"Hosted cloud microVM architecture."
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: CodeSandbox API vs Fly Machines
Architectural trade-offs and decision criteria
Is CodeSandbox API or Fly Machines cheaper for developers?
CodeSandbox API has a starting price of $18/mo (flat fee), while Fly Machines starts at $1.94/mo (usage based). CodeSandbox API includes a free tier (Free public sandboxes with session timeouts). Fly Machines offers a free tier (3 shared-cpu-1x microVMs allowance).
Can I self-host CodeSandbox API and Fly Machines in my own infrastructure?
CodeSandbox API is a cloud-managed service only. In comparison, Fly Machines is proprietary cloud infrastructure.
Do CodeSandbox API and Fly Machines support the Model Context Protocol (MCP)?
CodeSandbox API does not currently list native MCP server compatibility. Fly Machines does not advertise built-in MCP protocol bindings.
Which programming languages have official SDKs for CodeSandbox API vs Fly Machines?
CodeSandbox API provides official SDKs in: typescript, javascript. Meanwhile, Fly Machines supports: go, curl, python.