Modal closed a $750M Series D led by Accel at a $15.75B post-money valuation, 3.4x its $4.65B Series C in May. The signal: isolated environments where agents run the code they write have gone from an add-on to a standalone $300M-a-year business.
Daytona treats a sandbox as a long-lived computer that can start, pause, snapshot, and fork. It raised a $24 million Series A in 2026, while a Laude Institute case study reports 37,000 sandboxes in one week. It fits parallel evaluations and coding agents, but its core open-source repository is no longer maintained.
Runloop combines isolated microVMs, reproducible images, disk branching, credential proxies, and evals in one coding-agent platform; an official case study reports more than 10,000 concurrent Devboxes in one workload.
Sail Research lets each inference request declare a completion window, scheduling patient background agents on cheaper capacity, while Sailboxes provide persistent long-running execution environments.
An open-source coding agent reference implementation from Vercel Labs. A three-layer architecture separates the web UI, agent workflow, and sandbox VM — designed as a starting point for teams that want to self-host their own Claude Code or Cursor Background Agent.