Judge0 CE

Online code execution system

Open documentation ↗

API keyHTTPSCORSProgramming

Verified today: 100% uptime

API key

Required

HTTPS

Supported

Browser calls

Yes, CORS enabled

Status

Live · 100/100

Overview & Architectural Role

Judge0 CE provides programmatic access to online code execution system. Delivered over secure HTTPS protocols, it exposes structured endpoints designed to integrate cleanly into modern frontend frameworks, backend microservices, and automated data pipelines without requiring local database provisioning.

Who it is built for

Engineers building web dashboards, mobile applications, CLI utilities, or background cron workers in need of reliable programming data feeds.

Architectural Advantage

Consuming Judge0 CE removes the operational overhead of running custom scrapers, orchestrating headless browser fleets, or manually seeding and maintaining a local database. Instead of reverse-engineering volatile DOM layouts or dealing with anti-bot IP blocks, your application connects directly to a standardized JSON interface that supports client-side browser execution out of the box. Dedicated authentication ensures rate quotas and credential tracking per project environment.

What our checks found

Health score: 100/100
Reliability: 100%
Average latency: 1331ms

Last checked 2026-10-24. Measured independently, not self-reported by the provider.

Core Use Cases & Architecture Ideas

Practical real-world patterns for integrating Judge0 CE into software systems.

Automated SaaS Feature Integration

Embed data and functionality from Judge0 CE directly into application onboarding, profile enrichment, or reporting dashboards.

Architecture: Backend service worker fetches Judge0 CE during user workflows, caches responses in Redis, and hydrates UI state.

Scheduled Reporting & Monitoring Bot

Periodically extract updates from Judge0 CE to generate daily digests, analytics reports, or Slack notifications.

Architecture: A scheduled GitHub Action or cron worker executes a lightweight script calling Judge0 CE, formatting markdown summaries for stakeholders.

Rapid Prototyping & Hackathon Showcase

Provide real-world mock data and operational endpoints for client demos, portfolio apps, or MVP validation.

Architecture: Static client SPA queries Judge0 CE directly to populate mock dashboards, graphs, and interactive UI states without a custom backend.

Code Implementation Examples

Production-ready starting templates with error handling for Judge0 CE.

// Requires an API key. Check the docs for whether it goes in a header or a query parameter.
// Modern native fetch with error handling
async function callApi() {
  try {
    const response = await fetch('https://ce.judge0.com/api/v1/resource', {
      method: 'GET',
    headers: {
      'Authorization': 'Bearer YOUR_API_KEY',
      Accept: 'application/json',
    },
    });

    if (!response.ok) {
      throw new Error(`HTTP ${response.status}: ${response.statusText}`);
    }

    const data = await response.json();
    console.log('Response payload:', data);
    return data;
  } catch (error) {
    console.error('API request failed:', error);
    throw error;
  }
}

// callApi();

Response Payload & Live Testing

Inspect the expected JSON structure returned by Judge0 CE.

Expected JSON Response Payload

Authentic sample payload structure to evaluate schema attributes before integration.

{
  "status": 200,
  "api": "Judge0 CE",
  "endpoint": "/judge0-ce",
  "data": {
    "id": 101,
    "title": "Judge0 CE Sample Payload",
    "description": "Online code execution system",
    "verified": true,
    "category": "Programming",
    "updated_at": "2026-10-24T07:39:31.167Z"
  },
  "meta": {
    "response_time_ms": 1331,
    "cached": false
  }
}

Format: application/json

Integration Considerations & Best Practices

Technical factors to keep in mind when integrating Judge0 CE into production environments.

Implement In-Memory or Edge Caching

Avoid triggering rate limits on public feeds by caching response payloads in Redis, Vercel KV, or standard HTTP Cache-Control headers with a 5-to-15 minute TTL.

Shield Credentials in Backend Route Handlers

Never expose private API keys in client-side JavaScript or bundle environments. Proxy requests through a Next.js API route or serverless backend to keep secret keys out of public DevTools inspection.

Direct Client-Side Browser Support

CORS headers are validated and present on responses. You can safely call this endpoint directly from frontend React, Vue, or static HTML pages without an intermediary proxy server.

Validate HTTP Status Before Parsing JSON

Always inspect response.ok before executing response.json(). Upstream services returning 4xx or 502 Bad Gateway often serve HTML error pages, which cause syntax errors when parsed as JSON.

Where this listing comes from

Aggregated from one public source (public-apis), then normalised and checked by us.

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Judge0 CE — common questions

Answered from what our own scheduled checks found, not from the provider's marketing.

Is Judge0 CE free to use?

Judge0 CE is listed in our free catalogue, but it requires an API key, so you will need to register before your first call. Providers frequently reserve higher limits and commercial use for paid plans.

Does Judge0 CE need an API key?

Yes. Judge0 CE authenticates with an API key. Keep it server-side rather than in browser code, because anything in your frontend bundle is readable by anyone who opens developer tools.

Can I call Judge0 CE from browser JavaScript?

Yes. Judge0 CE returned CORS headers when we checked it, so a browser will let your page read the response. You can fetch it directly from client-side JavaScript with no proxy and no backend.

Is Judge0 CE still working?

Yes, as of 2026-10-24. Our automated check reached Judge0 CE and recorded a 100% reliability score with a median response time of 1331 ms. We re-check on a schedule, and this page updates with the result.

Is Judge0 CE available over HTTPS?

Yes. Judge0 CE serves over HTTPS, so you can call it from a secure page without triggering a mixed-content block.