I was referred to Udemy and they contacted me pretty soon after that.
After a phone screen, i got an online version of a whiteboard interview - I had to implement basic frontend functionality without IDE or code completion. Also some behavioral questions and theoretical ones.
The third step was to complete a task - develop a full stack web app in a week. From a database and REST API to Javascript frontend, HTML and CSS. Everything needed to be test covered, documented and secure. A script for setting up and running the project was considered a plus. The task was small but complex, the requirements had a lot of details that called for smart solutions and good understanding of database and OO design. Preferred technologies were Django and React, but both the technologies and the deadline were flexible. You could ask for more time or use any language or framework.
Basically you have to choose between completing everything and delivering a mediocre result, extending your deadline and spending all of your "me time" for weeks on something that might or might not result in a new job, or focusing on one aspect of the project and doing it perfectly, which seemed bad as this is for a full stack position. I chose the first and I wasn't happy with the result.
The final step was an onsite interview, four back to back interviews onsite - frontend, backend, design and product interview. 15 minutes behavioral questions, 45 minutes technical.
There were questions based on the project, as well as the classic "exam style" questions.
Although the questions themselves weren't too difficult, nothing too advanced and each interview was average in terms of complexity, the process was over complicated and stressful and basically a huge hassle. I would never agree to complete such a complex task for a company again. Most companies, including the Big ones, manage without this step, so there's no need for that amount of stress.
Finally, Udemy's website claims they respond within two days. In my case the recruiter was on a business trip and contacted me to let me know he'll update me the following week. I was rejected 9 days after the final interview. The feedback was very vague, but I'm sure they would have given me more information had I sent them a request for that. Everyone was very responsive, friendly and helpful throughout the whole process.