Code Sandbox X402 MCP Server

Code Sandbox API

Execute Python, JavaScript, or SQL in a sandbox. Get stdout, execution time, errors. 10s timeout. Pay-per-call via x402 (USDC on Base L2) -- no API key, no signup, no rate-limit wall.

Part of the klymax402 marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.

Quickstart -- MCP

Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):

{
  "mcpServers": {
    "code-sandbox": {
      "url": "https://code-sandbox.api.klymax402.com/mcp"
    }
  }
}

Quickstart -- HTTP (x402)

curl -X POST "https://code-sandbox.api.klymax402.com/api/execute" \
  -H "Content-Type: application/json" \
  -d '{"code":"...","language":"..."}'
# -> 402 Payment Required, with an x402 payment challenge in the response body

Any x402-aware client (@x402/fetch, x402-agent-tools, ATXP) handles the 402 -> sign -> retry cycle automatically.

Tools

code_execute_sandbox

Use this when you need to execute Python, JavaScript, or SQL code in a sandboxed environment and get the output. Supports Python (subprocess), JavaScript (eval), and SQL (in-memory SQLite).

Parameters

Returns

• output -- stdout captured from code execution (max 10KB)
• language -- the language that was executed
• executionTimeMs -- execution duration in milliseconds
• exitCode -- process exit code (0 = success)
• error -- error message if execution failed (null on success)

Example response:

{"output":"Hello World\n42\n","language":"python","executionTimeMs":234,"exitCode":0,"error":null}

When to use: running calculations, data transformations, validating code snippets, or querying in-memory databases. Essential when you need computed results rather than static data.

Example agent prompts

• "Execute Python, JavaScript, or SQL code in a sandboxed environment and get the output"

Payment

• Protocol: x402 -- HTTP-native pay-per-call, no signup, no API key
• Network: Base L2 (eip155:8453)
• Asset: USDC
• Facilitator: Coinbase CDP (primary), PayAI (fallback)
• Also reachable via ATXP (OAuth-wrapped x402, RFC 9728 protected-resource metadata)

Part of klymax402

100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.

• Catalog: https://klymax402.com/llms.txt
• Full API reference: https://klymax402.com/llms-full.txt
• Live stats: https://klymax402.com/stats

License

MIT