Execute Code

Run code securely in isolated sandbox environments. Each execution runs in its own isolated subprocess inside a Kata micro-VM with no network access.

Secure by Design

Code runs in isolated Kata micro-VMs with no network access. Each execution is ephemeral - environments are destroyed immediately after completion.

POST/v1/code-sandbox/execute

Execute code in an isolated code sandbox environment.

Request Body

Parameter	Type	Description
`code`required	string	The code to execute in the Code Sandbox
`language`required	"python" \| "javascript"	Programming language runtime to use

Example Request

cURL

Node.js

curl -X POST https://api.builde2e.com/api/v1/code-sandbox/execute \
  -H 'Content-Type: application/json' \
  -H 'Authorization: Bearer uc-YOUR-API-KEY' \
  -d '{
    "code": "print(sum(range(1, 101)))",
    "language": "python"
  }'

Example Response

json

{
  "stdout": "Hello, World!\n",
  "stderr": "",
  "exitCode": 0,
  "executionTimeMs": 95.23,
  "memoryUsageMb": 8.45,
  "timedOut": false,
  "cost": 0.002
}

Multi-line Code with Imports

You can execute multi-line code with imports and complex logic.

Python Example

bash

curl -X POST https://api.builde2e.com/api/v1/code-sandbox/execute \
  -H 'Content-Type: application/json' \
  -H 'Authorization: Bearer uc-YOUR-API-KEY' \
  -d '{
    "code": "import json\nimport math\n\ndata = {\n    \"name\": \"BuildE2E\",\n    \"version\": 1,\n    \"sqrt\": math.sqrt(16)\n}\nprint(json.dumps(data, indent=2))",
    "language": "python"
  }'

JavaScript Example

cURL

Node.js

curl -X POST https://api.builde2e.com/api/v1/code-sandbox/execute \
  -H 'Content-Type: application/json' \
  -H 'Authorization: Bearer uc-YOUR-API-KEY' \
  -d '{
    "code": "const data = [3,1,4,1,5,9]; console.log(JSON.stringify(data.sort((a,b) => a-b)));",
    "language": "javascript"
  }'

Example Response

json

{
  "stdout": "{\n  \"name\": \"BuildE2E\",\n  \"version\": 1,\n  \"sqrt\": 4.0\n}\n",
  "stderr": "",
  "exitCode": 0,
  "executionTimeMs": 142.56,
  "memoryUsageMb": 9.12,
  "timedOut": false,
  "cost": 0.002
}

Using the SDK

The Node.js SDK provides a simple interface for code execution:

javascript

import BuildE2E from '@builde2e/sdk';

BuildE2E.setApiKey('uc-YOUR-API-KEY');

// Python
const pyResult = await BuildE2E.executeCode({
  code: 'import numpy as np; print(np.array([1, 2, 3]))',
  language: 'python'
});

// JavaScript
const jsResult = await BuildE2E.executeCode({
  code: 'const _ = require("lodash"); console.log(_.chunk([1,2,3,4], 2));',
  language: 'javascript'
});

console.log(pyResult.stdout);          // "[1 2 3]\n"
console.log(jsResult.stdout);          // "[ [ 1, 2 ], [ 3, 4 ] ]\n"
console.log(pyResult.memoryUsageMb);   // 30.5

Response Fields

Field	Type	Description
`stdout`	string	Standard output from the code execution
`stderr`	string	Standard error output from the code execution
`exitCode`	number	Exit code (0 = success, 124 = timeout)
`executionTimeMs`	number	Time taken to execute the code in milliseconds
`memoryUsageMb`	number	Peak memory usage during execution in megabytes
`timedOut`	boolean	Whether the execution timed out
`error`	string	Error message if execution infrastructure failed
`cost`	number	Cost of the request in USD

Pre-installed Libraries

The following libraries are pre-installed and ready to use. No installation or network access is needed.

Python

Python 3.12 with the full standard library, plus:

numpypandassympypython-dateutilPillow

JavaScript

Node.js 22 with CommonJS modules (require() syntax), plus:

lodashdayjsmathjs

Pricing

Each code execution costs $0.002 USD (~$2.00 per 1000 executions). Cost is charged regardless of whether the code succeeds or fails.

Execution Limits

Code Sandbox executions have the following limits to ensure fair usage:

Limit	Value	Description
Timeout	10 seconds	Maximum execution time before timeout
Memory	256 MB	Maximum memory allocation per execution
CPU	0.5 cores	CPU allocation per execution
Code size	100 KB	Maximum size of submitted code
Output	1 MB	Maximum stdout/stderr output size
Network	None	No network access from sandbox

Error Handling

When code execution fails, the response will contain error information:

json

{
  "stdout": "",
  "stderr": "Traceback (most recent call last):\n  File "<string>", line 1, in <module>\nZeroDivisionError: division by zero",
  "exitCode": 1,
  "executionTimeMs": 45.12,
  "memoryUsageMb": 6.78,
  "timedOut": false,
  "cost": 0.002
}

When execution times out (exceeds 10 seconds):

json

{
  "stdout": "",
  "stderr": "",
  "exitCode": 124,
  "executionTimeMs": 10000,
  "memoryUsageMb": 12.34,
  "timedOut": true,
  "cost": 0.002
}