Dumbbell is a free iPhone app developed by Jiaqi Feng that falls under the Lifestyle category, specifically in Health & Fitness. This app provides users with the ability to design and personalize their own workout routines while also keeping track of their workout progress.

With Dumbbell, users can easily create their own workout routines by selecting from a wide range of exercises and organizing them in a way that suits their fitness goals. The app allows users to customize each exercise by specifying the number of sets, repetitions, and weights. This level of customization ensures that users can tailor their workouts to their specific needs and preferences.

One of the standout features of Dumbbell is its workout log. Users can log their workouts after each session, recording the exercises performed, sets, repetitions, and weights used. This log serves as a comprehensive record of the user's workout history, allowing them to track their progress over time. This feature is particularly useful for individuals who want to monitor their fitness journey and see improvements in their strength and endurance.

Overall, Dumbbell is a user-friendly app that empowers individuals to design their own workout routines and track their progress. Whether you're a beginner looking to establish a fitness routine or a seasoned gym-goer wanting to take control of your workouts, Dumbbell provides the tools necessary to achieve your fitness goals.