Ben Swerdlow is CEO and co-founder of Freestyle, which builds Linux VMs for AI agents. He joins Abhi Aiyer to explain why he refuses to call them sandboxes.

Freestyle runs on bare metal in a house. There is duplicated internet, a battery, a backup kerosene generator, a fingerprint-protected door, and a hole cut in a wall. The move followed a $45,000 cloud bill and the discovery that an old computer outperformed the cloud version of an early prototype.

Ben's advice to most of the audience is not to use his product. But he draws the line at execution time and names the case where a sandbox is simply the better tool.

His path to VMs ran through two abandoned products. A database engine built at Apple in evenings and carried through an entire YC batch was killed in November 2024 after an early o3 demo. A serverless JavaScript runtime with 10ms cold starts came next, and nobody wanted it.

You'll also learn why Freestyle moved off Firecracker and what rust-vmm makes possible, the destructive-snapshot problem that caused Ben real pain, and why stripped-down kernels break on Supabase.

📎 READ MORE
Freestyle: https://www.freestyle.sh
Freestyle VMs: https://www.freestyle.sh/products/vms
Ben on LinkedIn: https://www.linkedin.com/in/benswerdlow
rust-vmm: https://github.com/rust-vmm/community

📚 MASTRA RESOURCES
https://mastra.ai
https://x.com/mastra_ai
Discord: https://mastra.ai/community/discord
GitHub: https://github.com/mastra-ai
Learn Mastra: https://mastra.ai/learn
Principles of Building AI Agents: https://mastra.ai/books/principles-of-building-ai-agents
Patterns of Building AI Agents: https://mastra.ai/books/patterns-of-building-ai-agents

WHAT IS MASTRA
Mastra is an open-source TypeScript framework designed for building and shipping AI-powered applications and agents with minimal friction. It supports the full lifecycle of agent development — from prototype to production.

AI Agents Hour is a weekly livestream by Mastra CPO Shane Thomas and CTO Abhi Aiyer. Mondays 12PM Pacific.

⏱️ CHAPTERS
00:00 Cold open
00:32 Ben Swerdlow, Freestyle
00:45 Why "sandbox" is the wrong word
00:58 The serverless JavaScript runtime nobody wanted
01:35 Apple, YC, and the database they killed
03:11 Running server racks in a house
05:43 What it takes to operate that
07:20 Agent VM vs. sandbox
08:07 Background agents and the 8GB ceiling
10:13 Firecracker, rust-vmm, and destructive snapshots
12:01 Demo
14:02 Networks and VPN APIs
16:22 Who should not use Freestyle
17:09 Virtualizing themselves on every PR
7:28 What Ben would tell you to build for