Exercism is an open source, free platform that provides developers of all backgrounds with an opportunity to practice and improve their coding skills. It offers an array of coding exercises and challenges in a variety of different programming languages. Exercism also provides users with the ability to review and discuss each exercise with other developers around the world, in order to gain insight into different approaches and techniques. As users progress through each exercise, they receive feedback as well as suggestions on how to improve their code. Exercism also provides users with the opportunity to earn badges and recognition for their accomplishments.
So much variety for beginners. You can see crypto, interface design, python, stocks, etc.