12 LANGUAGES. ONE API.

Execute code from any app or AI agent

Run Python, Java, C++, Go, Rust, and 7 more languages in sandboxed containers. REST API, WebSocket, or MCP for AI agents.

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12 Languages, Always Up to Date

Latest compiler and runtime versions, maintained and updated regularly.

Py

Python

3.14

C

C

GCC 15

C+

C++

G++ 15

Ja

Java

OpenJDK 25

C#

C#

.NET 9

F#

F#

.NET 9

Go

Go

1.26

Ru

Rust

1.93

PH

PHP

8.5

Ru

Ruby

4.0

Ha

Haskell

9.12

Ty

TypeScript

Deno

Built for Developers

Everything you need to add code execution to your application.

Sub-second Execution

Code runs in pre-warmed Docker containers. Get results back in milliseconds via callbacks or WebSockets.

Fully Sandboxed

512MB RAM, 2 CPUs, 64 PIDs max, 30s timeout, no network access. Every execution is completely isolated.

Simple REST API

One endpoint. Send code, get results. Authenticate with an API key in the Authorization header.

AI-Native (MCP)

Connect Claude, Cursor, VS Code, or any MCP client with a single URL. AI agents can execute code directly.

Real-time WebSocket

Get execution results pushed to your app instantly via Socket.IO. Perfect for interactive coding experiences.

Embeddable Widget

Drop a code editor widget into any webpage. Users write and run code without leaving your site.

Production Ready

Battle-tested infrastructure with Celery job queues, automatic retries, and comprehensive error handling.

Three Steps. That's It.

1

Get an API Key

Sign up with Google, create an app, and get your API key in seconds.

2

Send Code

POST to our API with a compiler name, code, and optional input. One endpoint.

3

Get Results

Receive output, errors, CPU, and memory stats via callback URL or WebSocket.

Start in Minutes

Pick your language. Copy. Paste. Run.

Request

Terminal
curl -X POST https://api.onlinecompiler.io/api/run-code/ \
  -H "Authorization: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "compiler": "python-3.14",
    "code": "print(\"Hello, World!\")",
    "input": ""
  }'

Callback Response

JSON Response
{
  "output": "Hello, World!\n",
  "error": "",
  "status": "success",
  "exit_code": 0,
  "signal": null,
  "time": "0.0248",
  "total": "0.0330",
  "memory": "8192"
}

Secure by Design

Every execution runs in an isolated Docker container with strict resource limits.

2

CPU Cores

512MB

Memory

30s

Timeout

None

Network Access

Ready to start building?

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