If you're interested in HIIT (High-Intensity Interval Training) Exercises, check out these apps that will help you with timing. High-Intensity Interval Training includes short bursts of intense training followed by low-intensity recovery periods. HIIT Exercises have multiple benefits including improving metabolism and burning more calories in a shorter amount of time.
Nike Training Club- This app is Coach Wilson's FAVORITE workout app! There are 185+ free workouts ranging from 5 to 50 minutes. Most of the workouts are HIIT structured. You can choose a muscle group to focus on and browse exercises to find one with or without equipment that works best for you! They also have "live classes" which are videos of workout classes you can follow along with!
Johnson & Johnson Official 7 Minute Workout app- Another 7 minute HIIT app focused on building strength and endurance. Has great videos to demonstrate workouts and can send you reminders to workout.
Keelo App- This app provides 16 free short but intense workouts that burn lots of calories quickly. This app allows you to workout with or without equipment and is easy to use.
Seven App- Creates 7 minute workouts for you based on your fitness goals. This is an intense but more manageable way to get some exercise in every day. There are in-app purchases, but some workouts accessible for free.