Why agent sandboxes became a thing: slow VMs pushed Lovable, E2B and Modal to build their own
vboykis · x · 2026-10-19
Phil Eaton's deep dive maps the emerging agent sandbox market. As coding agents and AI products let LLMs generate and run code, the industry converged on one isolated environment per task or even per request.
- Slow VM startup and Lambda's 15-minute limit gave Modal, Baseten and E2B a head start over cloud providers
- Lovable ran one fly.io machine per project in 2025, then moved at "massive scale" to Modal; it's now hiring a Staff Engineer to build a gVisor-based runtime and a high-throughput sandbox scheduler across clouds — possibly a cost-driven migration
- Excel gives each workbook a container inside a VM; agents get a gVisor container per session
- Funding: fly.io raised a $25M Series D and pivoted to agent sandboxes (Sprites); exe.dev raised $35M total; E2B $21M; Daytona $24M; Together AI acquired CodeSandbox
- The tech stack spans gVisor, Firecracker, Cloud Hypervisor, KVM, Kata Containers and QEMU
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