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Introduction

The Runtime API provides a simple REST interface for executing code snippets in isolated Docker containers across multiple programming languages. The API is built with Spring Boot and runs on port 8081 by default.

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Base URL

The API is available at: 
http://localhost:8081/api
For production deployments, replace localhost:8081 with your server’s hostname and port.

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API Architecture

The Runtime API follows a straightforward request-response pattern:
  1. Submit Code - Send a code execution request with your code snippet and target language
  2. Isolated Execution - Code runs in a secure Docker container with resource limits
  3. Receive Results - Get output, exit code, and execution time in the response

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Response Format

All API responses follow a consistent wrapper format using the ApiResponse<T> structure: 
{
  "success": true,
  "message": "Execution successful",
  "data": {
    // Response data specific to the endpoint
  }
}

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Response Fields

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success
boolean
required
Indicates whether the API request was successful
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message
string
required
Human-readable message describing the result
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data
object
The actual response payload (type varies by endpoint)

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Supported Languages

The Runtime API supports code execution in the following languages:
  • Java - JDK-based execution
  • Python - Python 3 interpreter
  • C - GCC compiler
  • C++ - G++ compiler
  • JavaScript - Node.js runtime

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Quick Example

Here’s a complete example of executing a Python script: 
curl -X POST http://localhost:8081/api/execute \
  -H "Content-Type: application/json" \
  -d '{
    "code": "print(\"Hello from Runtime!\")",
    "language": "python"
  }'
Response: 
{
  "success": true,
  "message": "Execution successful",
  "data": {
    "output": "Hello from Runtime!\n",
    "exitCode": 0,
    "executionTime": 245
  }
}

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Resource Limits

All code executions are subject to resource constraints to ensure system stability:
  • Memory - Limited per container
  • CPU - Constrained CPU usage
  • Execution Time - Automatic timeout and cleanup
  • Network - Isolated network environment
Resource limits are enforced at the Docker container level. Long-running or resource-intensive code may be terminated automatically.

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Error Handling

When an error occurs, the API returns a response with success: false: 
{
  "success": false,
  "message": "Error description",
  "data": null
}
Common error scenarios include:
  • Invalid or unsupported language
  • Code compilation errors
  • Runtime exceptions
  • Resource limit violations
  • Docker container failures

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Next Steps

Authentication

Learn about API authentication and security

Execute Endpoint

Detailed documentation for the code execution endpoint

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