Sandflare – I built a sandbox that launches AI agent VMs in ~300ms

Description

I've been building Sandflare for the past few months — it launches Firecracker microVMs for AI agents in ~300ms cold start. The idea came from running LLM-generated code in production. Docker felt too risky (shared kernel), full VMs too slow (5–10s). Firecracker hits the middle: real VM isolation, fast boot. I also added managed Postgres because almost every agent I built needed persistent state. One call wires a database into a sandbox. There are great tools in this space already (E2B,