Calm - Calm.com can help you reduce stress and increase calm.
Relax.li - Pure relaxation in your browser
Headspace - Meditation made simple. Brilliant things happen in calm minds.
Relaxify - Science-Based Mental Fitness & Well-Being Psychology Mobile App
Relay - An extension that adds Discord-style chat to every website
Sound-To-Calm - A stress relief site to stay calm and carry on.