5K to 10K is a free Android app developed by Active Network LLC, designed to help users who have completed the Couch to 5K program, or those who are already 5K-ready, to train for a 10K race in just nine weeks. The app features three different virtual coaches - Constance, Billie, and Sergeant Block - to motivate and support users in every workout.

With real-human audio cues, users are guided through each workout, while an in-app music player allows them to enjoy their favorite playlists. The app also provides free GPS support, allowing users to calculate their distance and pace and map their routes with ease. Moreover, users can gradually challenge themselves with progressively faster paces and log their workouts to track their progress.

Overall, 5K to 10K is an excellent app for anyone who wants to train for a 10K race in a structured and effective way. However, it's important to note that the app and any information provided by Active Network Inc. are for informational purposes only and should not be considered a substitute for professional medical advice. Before starting any fitness program, users should consult their healthcare provider, and particularly for the activities and exercises described in the app, consulting with a licensed physician is essential to avoid injury or death.