Best Agent Sandboxes (2026)

Agent sandboxes are the secure, isolated runtimes where AI agents do their work. When an agent writes and runs code, browses the web, or calls tools, it needs an environment that is disposable, locked down, and fast to spin up, so a mistake or an attack cannot reach the host or production systems. StartupHub.ai ranks the companies building this layer by funding and traction. The category covers a few shapes. Some provide code-execution sandboxes that run untrusted, model-generated code in milliseconds. Others offer full cloud development environments that an agent can drive end to end. A third group sandboxes the browser, so web agents can click and type in isolation. The shared requirements are strong isolation, fast cold starts, and clean teardown. This is foundational infrastructure for the agent era, because autonomy is only safe inside a boundary. The winners will pair tight security with developer-friendly APIs and pricing that scales to millions of short-lived sessions. As agents move from demos to production, the sandbox becomes one of the most critical pieces of the stack. This page updates as new entrants and funding appear.