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Deno
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.

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Setup

The deno binary ships inside the arizephoenix/phoenix container, so there’s nothing to install there. If you run Phoenix another way — for example pip install arize-phoenix — install Deno yourself so the deno binary is on the PATH of the process running Phoenix:
Restart Phoenix, then open Settings → Sandboxes. The Deno row should read Available. If it shows “Unavailable — Deno binary isn’t installed,” the Phoenix process can’t find deno on its PATH. For the full platform details, see Sandbox Backends.

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What it supports

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

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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.