5K Run - Couch to 5K is a free health and fitness app designed to help users run a 5K. The app uses the interval training method to gradually improve users' stamina and endurance over an 8-week period. Users start with 1-minute jogging intervals with 1.5-minute walks in between and gradually progress to more challenging runs. The app prompts users to run or walk over their headphones or speakers and provides important information such as the time elapsed, time remaining, and current interval.

One of the app's standout features is that it allows users to play their favorite music from any music app while running, and the coach's prompts chime in over the music. Additionally, the app can be used both outside and on a treadmill, and users can pause their run or go to different intervals using the back/next buttons. The app also offers a running plan overview, which allows users to look ahead and see future runs, and Apple Health support, which syncs users' runs to the Health app for a better view of their overall fitness.