Overview
Modal is a serverless platform for running code in the cloud without managing servers. For agents, Modal Sandboxes spin up an isolated container on demand, run arbitrary model-generated code inside it, and stream back the output — the host is never exposed.
flowchart LR code[LLM code] --> modal[Modal Sandbox] modal --> exec[(isolated container)] modal --> out[stdout / results]
You define the environment in Python (image, resources, timeout); Modal schedules it on its infrastructure and bills per second of compute. The SDK is open (Apache-2.0); the hosted runtime is the paid service.
When to use it
Reach for Modal when an agent needs to execute untrusted code, but you also want the same primitive to scale to heavier jobs — GPU workloads, batch runs, or hosting a tool as a serverless function — behind one Python SDK, without operating sandboxes yourself.