Langtern is the Chinese language app for students and teachers:
Student: helps you learn Chinese by assisting you when navigating Chinese web pages, watching videos in Chinese, or reading ebooks/PDFs in Chinese. These functionalities are completely free, although there are other advanced student functionalities under a small subscription, like online content search by HSK level.
Teacher: makes it easy to create exercises automatically from online material with artificial intelligence. Your students can do their exercises interactively through the app. These functionalities are available under a subscription.
The terms of service can be found at: https://langtern.com/public/doc/en/tos.html