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Common Problems
Design a Fitness Tracking App Like Strava
Understanding the Problem
While Strava supports a wide variety of activities, we'll focus on running and cycling for this question.
Functional Requirements
Core Requirements
- Users should be able to start, pause, stop, and save their runs and rides.
- While running or cycling, users should be able to view activity data, including route, distance, and time.
- Users should be able to view details about their own completed activities as well as the activities of their friends.
Below the Line (Out of Scope)
- Adding or deleting friends (friend management).
- Authentication and authorization.
- Commenting or liking runs.
Non-Functional Requirements
Core Requirements
- The system should be highly available (availability >> consistency).
- The app should function in remote areas without network connectivity.
- The app should provide the athlete with accurate and up-to-date local statistics during the run/ride.
- The system should scale to support 10 million concurrent activities.
The Set Up
Planning the Approach
Defining the Core Entities
The API
High-Level Design
1) Users should be able to start, pause, stop, and save their runs and rides.
2) While running or cycling, users should be able to view activity data, including route, distance, and time.
3) Users should be able to view details about their own completed activities as well as the activities of their friends.
Potential Deep Dives
1) How can we support tracking activities while offline?
2) How can we scale to support 10 million concurrent activities?
3) How can we support realtime sharing of activities with friends?
4) How can we expose a leaderboard of top athletes?

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