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Code Sandbox API

Official registry Developer tools

Execute Python, JavaScript, SQL code in a sandbox. x402 micropayment.

Source code Website Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

Remote (sse)
Claude Code 
claude mcp add --transport sse code-sandbox-api 'https://code-sandbox.api.klymax402.com/mcp'
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "code-sandbox-api": {
            "type": "sse",
            "url": "https://code-sandbox.api.klymax402.com/mcp"
        }
    }
}

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. Code Sandbox API
  2. Quickstart -- MCP
  3. Quickstart -- HTTP (x402)
  4. Tools
  5. Example agent prompts
  6. Payment
  7. Part of klymax402
  8. License

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

ToolMethodPathPriceDescription
code_execute_sandboxPOST/api/execute$0.02Execute 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

NameTypeRequiredDescription
codestringyesThe code to execute
languagestringyesProgramming language: python, javascript, or sql
timeoutnumbernoExecution 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:

{"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.

License

MIT

Frequently asked questions

What is Code Sandbox API?

Execute Python, JavaScript, SQL code in a sandbox. x402 micropayment.

How do I install Code Sandbox API?

It runs as a remote server. In Claude Code: claude mcp add --transport sse code-sandbox-api 'https://code-sandbox.api.klymax402.com/mcp'. For other clients, paste the JSON configuration from this page into their MCP settings.

Does Code Sandbox API need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is Code Sandbox API open source?

Yes. Its code is on GitHub under the MIT license.

Who maintains Code Sandbox API?

It is published by Br0ski777. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.