Judge0 is an open-source project that focues on building online tools and services for executing and grading untrusted source code in programming contests, education and research.
Main product of Judge0 is Judge0 API - free and open-source Web API for executing and grading untrusted source code. If you want to build your own online judge, but you don't know how to build sandbox environment - Judge0 API is perfect for you! It features more than 25 different compilers and interpreters. It is fast, robust and reliable. You can also self-host your own instance of Judge0 API and configure it to your own needs.
Second most important product of Judge0 is Judge0 IDE - free online IDE which enables users to run their code online. It uses Judge0 API - which means users have more than 25 different compilers and interpreters available to use.
Judge0 also provides some useful information about their services:
Judge0 Data shows you all relevant information about Judge0 API. There you can see how many submissions have been made, what is the most frequent language used, and what is the most frequent submission status.
Judge0 Status is official status page for all Judge0 services. There you can see uptime of all our relevant services.
Everything that Judge0 does is open-sourced and available on GitHub.