Judge0 CE

API

Free REST API for online code execution

Overview

Judge0 CE is a free, open-source online code execution system offering RESTful endpoints to run code in over 60 programming languages. Key endpoints let you submit code (with optional input) and retrieve results including stdout, stderr, execution time, memory usage, and exit codes. Responses are JSON-formatted. Use cases include building coding platforms, educational tools, online judges, or integrating code execution into apps. It supports self-hosting for custom deployments or public instance access.

Example Integration (JavaScript)

script.js JS


fetch('https://ce.judge0.com/')
  .then(res => res.json())
  .then(data => console.log(data))
  .catch(err => console.error(err));

Key Features

RESTful API
Supports 60+ programming languages
JSON response format
No API key required (public instance)
Execution metrics (time, memory)
Open-source (self-hostable)

Frequently Asked Questions

? Is Judge0 CE free to use?

Yes, the public instance of Judge0 CE is free for general use. It’s also open-source, so you can self-host it at no cost.

? Does it require an API Key?

The public instance doesn’t require an API key for basic requests, though rate limits apply to prevent abuse. Self-hosted instances can be configured with keys if needed.

? What is the response format?

All responses are in JSON, including execution status, stdout, stderr, execution time (seconds), and memory usage (kilobytes).

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Tool Info

Pricing Free

Category Programming

Platform Public API

Pros

⊕ Easy to integrate
⊕ Wide language support
⊕ Open-source (self-host option)
⊕ Free public access
⊕ Detailed execution results

Cons

⊖ Rate-limited public instance
⊖ No official SLA
⊖ Limited advanced features vs paid tiers
⊖ Setup required for self-hosting