Calm - This is a great way for beginners to start meditation. Choose between options for sound and length of time, as well as scenes from nature for you to visually focus on while you meditate. Guided as well as unguided sessions.
Headspace - Good for beginners just learning the art of meditation. Their level one course features easy, 10-minute sessions for each day that will help you get into the habit of meditating regularly. There are reminders, and you can choose to focus on aspects like foundation, health, and performance.
Insight Timer - Good for both beginners and experienced practitioners. Can select the length of time. Includes music traces, and ambient sounds. Discussion groups and community features.
UCLA Mindful - Provides guidance of the UCLA Mindful Awareness Research Center. Scientific research shows mindfulness can help manage stress-related physical conditions, reduce anxiety and depression, Basic Meditations for getting started, informative videos exploring how to get started, supportive meditation postures, and the science of mindfulness. Weekly podcasts from UCLA's Hammer Museum-- a 30 minute meditation on different themes you can search for and bookmark.
Healthy Minds Program - With a combination of podcast-style lessons and both seated and active meditations, you’ll learn what the science says about the brain while developing skills to tap into these learnings for a healthier, happier life. The program measures your current level of well-being and how it changes.