Blog

Our new websites

October 18, 2025

Hey guys! We just completed building our new websites that will be used for Code Joint courses. First, we have judge.codejoint.org, our online judging website similar to USACO where students will be submitting their code. Here is video demonstration of it:

The online judge was a lot of effort to create. Fortunately, thanks to a Brian Dean, director of USACO, we learned that we could use IOI's Isolate to sandbox code to prevent any potential security issues. We decided to build our website using Typescript, ExpressJS, and MongoDB for their ease of use. Additionally, we used EJS to make HTML more convenient. With these tools, we built a website that has:

• A comprehensive problemset full of problems
• An embedded code editor to write your code
• An account system to keep track of your submissions
• A satisfying submission animation

We learned a lot building this website, and you can see the effort we put in on our public Github repository for the online judge here. Next up is our course website, which allows students, parents, and teachers to track progress. Here's a video demonstration: course.codejoint.org, which we also have a video of:

We worked hard to ensure you parents and students could easily track progress on our website, which we built with the same tools we used for our online judge. Here's a list of features it has:

• Ability for teachers to assign problems to do
• Allows students to see what problems they need to do
• Allows teachers to see where students are struggling
• Allows for parents to track their child's progress

Overall, we hope that the effort we put into these websites will help accelerate the learning process and be a net benefit for everyone.