I took a couple short online classes last month:

• Get into DevOps: The Masterclass from Udemy. A nice overview of DevOps technologies, including as Ansible, Chef, Puppet, Terraform, AWS, Google Apps, and GitLab.
• Offline Web Applications by Google from Udacity. A pretty deep dive into Progressive Web Apps (PWAs), which I consider a game-changer as far as web site performance, offline experience, and promoting web apps to first-class applications.