Judge0 CE

A self-hosted API that compiles and runs untrusted code in a sandbox, for coding exercises, online judges, assessments and AI agents.

4.5k stars, 942 forks HTML On GitHub since January 2017

Visit website View on GitHub How to run it

Judge0 CE at a glance

Open sourceYes, GPL-3.0No paid parts in the repository
Health35 of 100Actively developed
Self-hostingDockerCompose file, 4 services
InterfaceEnglish onlyNo translation files found
Issue repliesWithin ~5 hoursMedian first reply; 17% of recent issues answered

What is Judge0 CE?

Judge0 CE is a code execution service you call over a simple HTTP JSON API or its official Python SDK. You send source code, optional extra files, compiler flags, command-line arguments and time or memory limits; it compiles and runs the program in a sandbox and returns detailed results, optionally through a webhook. It supports more than 90 languages and multi-file projects. Typical users build programming courses, competitive programming sites, hiring tests, browser IDEs and agents that need to run generated code. A sibling flavor, Judge0 Extra CE, lives on a separate branch and mainly differs in its language set.

Good fit if

  • You run an e-learning or interview platform and want to grade submissions on your own servers instead of paying per execution.
  • An AI agent or tool you build has to execute model-written code safely.

Look elsewhere if

  • You want a full browser IDE for your developers rather than an execution API: code-server.
  • You need interactive notebooks for data work: JupyterLab.

Before you adopt it

Judge0 is under GPL-3.0, and the repository contains no paid parts; the authors also offer a managed Judge0 Cloud. One developer writes almost all of the commits, and the last tagged release, v1.13.1, dates from April 2024, so check recent activity before relying on it. Self-hosting relies on a four-service Docker Compose file that includes PostgreSQL and Redis.

Drafted with AI from the project's README and repository data, then checked against that data on 7 November 2026. Report a correction

How to run Judge0 CE yourself

Docker
Dockerfile or compose file in the repository
Compose file
docker-compose.yml: 4 services (postgres, redis)
Setup effort
3 of 5, judged from the compose file
Kubernetes
No Helm chart in the repository
Desktop and mobile
No app builds in GitHub releases
Interface languages
English only

Install instructions: judge0.com or the README on GitHub.

Judge0 CE health: is it still maintained?

35 of 100, actively developed

Release rhythmNone in 12 monthsLatest: v1.13.1, 18 April 2024
Issue repliesWithin ~5 hoursMedian first reply; 17% of recent issues answered
Bus factorHigh riskThe most active of 2 authors wrote 91% of recent commits
  • Activity
    11 commits in the last 90 days, the latest on 26 October 2026.
    13 / 30
  • Contributors
    2 people wrote the 11 commits of the last 90 days; the most active wrote 91% of them.
    4 / 20
  • Releases
    0 releases in the last 12 months; the latest, v1.13.1, on 18 April 2024.
    1 / 20
  • Replies to issues
    Maintainers answered 17% of recent issues, with a median first reply after 5 hours.
    13 / 20
  • Security practices
    OpenSSF Scorecard 3.5 of 10.
    4 / 10

Read from GitHub on 7 November 2026. How the score works

Judge0 CE security practices

OpenSSF Scorecard checks how a project is developed and released: reviews, protected branches, pinned dependencies, signed releases. It does not audit the code itself.

OpenSSF Scorecard3.5 of 10How the project is built and released
Security policyYesExplains how to report a vulnerability
Signed releasesNoDownloads cannot be checked against a signature

What each check found

  • License file10 / 10A license file is present
  • Maintained10 / 10Steady commits and issue activity in the last 90 days
  • Security policy10 / 10Explains how to report a vulnerability
  • Binary files9 / 10A few compiled binaries are checked into the repository
  • Best-practices badge0 / 10No OpenSSF Best Practices badge
  • Branch protection0 / 10The main branch has no protection rules
  • Code review0 / 10Changes are merged without review
  • Fuzzing0 / 10No fuzz testing found
  • Pinned dependencies0 / 10Dependencies are not pinned to fixed versions
  • Signed releases0 / 10Releases are not signed
  • Static analysis0 / 10No static analysis found

From the OpenSSF Scorecard of 19 October 2026. Checks that do not apply to Judge0 CE are left out.

Judge0 CE license: is it open source?

Judge0 CE uses GPL-3.0, an open-source license approved by the OSI.

  1. January 2017First published on GitHub.
  2. TodayGPL-3.0.

Judge0 CE for developers

Written in

  • HTML 66%
  • Ruby 31%
  • Shell 3%
  • Dockerfile <1%

Getting involved

Contributing guideNot foundNo CONTRIBUTING file in the repository
Open issues171On GitHub
Authors, 90 days2Of 11 commits

Language shares are GitHub’s count of the code in the repository.

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Questions about Judge0 CE

Is Judge0 CE open source?

Yes. Judge0 CE is published under GPL-3.0, an OSI-approved open-source license.

Is Judge0 CE still maintained?

Its health score is 35 of 100 (actively developed). It had 11 commits in the last 90 days, the latest on 26 October 2026, and its latest release came out on 18 April 2024.

How do I run Judge0 CE?

You can run it with Docker. The README on GitHub has the exact steps.

What is Judge0 CE written in?

Judge0 CE is written mainly in HTML (66% of the code), with Ruby (31%), by GitHub’s count of the repository.

What are the alternatives to Judge0 CE?

Close alternatives in the Developer tools category include code-server, Centrifugo, Livebook.