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.):

json

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

Quickstart -- HTTP (x402)

bash

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

Tool	Method	Path	Price	Description
`code_execute_sandbox`	POST	`/api/execute`	$0.02	Execute code in a sandboxed environment

`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

Name	Type	Required	Description
`code`	string	yes	The code to execute
`language`	string	yes	Programming language: python, javascript, or sql
`timeout`	number	no	Execution timeout in milliseconds (default: 5000, max: 10000)

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:

json

{"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)