Blekline is Layer 4 — mask, enforce, and audit MCP tool calls. These providers are Layer 1 — isolated runtimes where agents execute code. Wire any of them through @blekline/mcp-proxy using BLEKLINE_DOWNSTREAM_MCP_COMMAND.
Comparison
| Provider | Best for | MCP / wiring | GPU | Edge / global |
|---|---|---|---|---|
| Daytona | Dev/agent workspaces, fast startup | @daytona/mcp-server | — | Multi-region |
| Modal | Serverless sandboxes, ML/GPU workloads | Community MCP servers | Yes | Cloud |
| Vercel Sandbox | Next.js / Vercel stack, Firecracker microVMs | @vercel/sandbox SDK + optional MCP | — | Vercel network |
| Cloudflare | Edge agents, Containers + Sandbox SDK | Sandbox SDK, Container MCP | — | Global edge |
| E2B | Firecracker microVMs, Fortune-500 scale | @e2b/mcp-server / E2B MCP | — | Cloud |
Universal proxy env
BLEKLINE_WORKSPACE_TOKEN=blw_...
BLEKLINE_DOWNSTREAM_MCP_COMMAND=npx,-y,@daytona/mcp-server # provider-specific
BLEKLINE_DOWNSTREAM_SERVER=daytona # telemetry label
Set BLEKLINE_MCP_PROXY_MOCK=1 for local dev without provider API keys.
Smoke tests
From blekline-oss:
SANDBOX_PROVIDER=daytona pnpm demo:sandbox-smoke
SANDBOX_PROVIDER=e2b pnpm demo:sandbox-smoke
# modal, vercel, cloudflare — see demo/README.md
When to pick which
- Daytona — default for coding agents, MCP-native, sub-90ms sandboxes, strong dev UX.
- Modal — GPU inference, Python-heavy agents, 50k+ concurrent sandboxes.
- Vercel Sandbox — already on Vercel; AI-generated code in isolated microVMs alongside Next.js apps.
- Cloudflare — edge-first agents, Workers + Containers, Code Mode MCP pattern.
- E2B — mature Firecracker isolation, broad enterprise adoption.
Next steps: AI Enablement Stack · MCP proxy · Quick start · Open workspace