Deno

Run simple TypeScript code evaluators locally inside the Phoenix server.

The Deno sandbox is a local sandbox for simple TypeScript evaluators — pure-logic checks like regex matches, JSON parsing, and scoring functions. It runs locally inside the Phoenix server, starts in milliseconds, and needs no credentials.

Configure it from Settings → Sandboxes.

What it supports

The Deno sandbox runs your TypeScript in a locked-down local process. It is intentionally limited to self-contained code:

Capability	Supported?
Environment variables	❌ Not supported — use a hosted sandbox
Network access	❌ Not supported — use a hosted sandbox
Third-party dependencies	❌ Not supported — use a hosted sandbox

If your evaluator needs any of the above, it cannot run on Deno. Use a hosted sandbox (E2B, Daytona, Vercel, or Modal) instead — those run each evaluation on an isolated remote VM with full support for environment variables, outbound network access, and installed packages.

Running untrusted code

The Deno sandbox is tightly restricted, but it runs in the Phoenix server process, so it is not a substitute for running untrusted code on isolated infrastructure. The script shares CPU and memory with Phoenix, and the security boundary depends on Deno itself. If you need to evaluate code from sources you cannot verify, use a hosted sandbox.