MimiBox: Turn browsers into sandbox for AI agents.

WASM-sandboxed code execution. Python and JavaScript, no containers, no VMs.

Install

npm install -g mimibox

Or run directly:

npx mimibox python 'print("hello")'

Usage

# Inline code
mimibox python 'import math; print(math.pi)'
mimibox js 'console.log("hello")'

# From file
mimibox python -f script.py
mimibox js -f app.js

# From stdin
echo 'print("hello")' | mimibox python
cat script.js | mimibox js

# Options
mimibox python --timeout 10000 'slow_function()'
mimibox js --memory 100 'big_computation()'

Exit codes

• 0 — success
• 1 — execution error
• 2 — bad arguments

Output

• stdout — execution output
• stderr — errors

How It Works

• Python — Pyodide (CPython 3.12 compiled to WASM)
• JavaScript — QuickJS via quickjs-emscripten (WASM)

Both run entirely inside WASM. No filesystem access, no network access from inside the sandbox.

Security

• Python: jsglobals: Object.create(null) blocks sandbox escape to Node.js globals
• JavaScript: QuickJS runs in a true WASM sandbox with no host access
• Timeout: 30s default, configurable via --timeout
• Memory: QuickJS 50MB default, configurable via --memory
• Output: truncated at 1MB

Browser Playground

A browser-based playground is also included at public/index.html — open it directly or serve it:

npx serve public

File Structure

src/
  cli.ts          CLI entry point
  python.ts       Pyodide wrapper
  javascript.ts   QuickJS wrapper
public/
  index.html      Browser playground

License

Apache License 2.0