Ask HN: Webapp like CodeSignal.com or leetcode.com. how to implement a compiler?

Hello all,

Maybe one or the other can give me a hint.

My goal is to create a Webapplication like codesignal or leetcode for my final project of a 3months-coding-bootcamp.

I want to code it with Java, Spring boot, html, css and Javascript.

A Admin of this page should be able to upload problems/cases with test-cases.

A user should be able to write his code in a given method and once he submitted, the test cases should run his code.

But i am struggling how to approach it. Like how can i implement a compiler in this construct?

Thank you very much in advance.