The candidate Interface is very self intuitive. Once they click on the link to take the test they are taken to a page where they answer the additional information requested by the company the candidate is interviewing for. Before starting the test candidates have the ability to take a demo test to get familiar with the platform. One thing to note is that the actual test doesn't start right after a demo session finishes, the candidate can choose to start the test whenever he/she feels comfortable.
The candidate can choose to translate the question's description in the language of preference if it is available, they can also use the language they want to code if they are left open as a choice by the company. After writing the code candidate can run it as many times as they want by clicking on "Run tests". They can also add their custom test cases in the interface to test their solution.