Design a fitness tracker app like strava
PremiumMobile systemMedium
- Background GPS recording
- Foreground service
- Crash safe recording
Quick answer
This mobile system interview question asks you to design a fitness tracker app like strava. Aim for a design that meets its requirements at the stated scale, then explain its main components, data flow and trade-offs. Interviewers want to see how you scope the problem, size it and defend each choice.
The problem
Design a fitness tracker app like Strava for iOS and Android. It records runs and rides with GPS while the phone is locked in a pocket, shows live pace and distance, and uploads the activity when a network is available. The hard parts are background location limits, battery, losing nothing if the app crashes and accurate distance from noisy GPS.
The activity service is a given API. Design the app.
What must a fitness tracker app like strava do?
- Record: Start, pause, resume and finish a run, ride or walk; recording continues with the screen locked or another app in front.
- Live stats: Show time, distance, current pace and lap splits while recording, and speak a split every kilometre.
How well must it do it?
- No gaps: No missing stretch longer than 10 seconds in a recording, even in the background.
- Battery: Under 8% battery per hour while recording with the screen off.
What scale should you design for?
Use these numbers in your estimates.
The scale numbers unlock with this questionUnlock
Key concepts
- Background GPS recording
- Foreground service
- Crash safe recording
- GPS filtering
- HealthKit
- Health connect
How you’ll practise
- Requirements
- App architecture
- Data and offline sync
- Networking and push
- Performance, battery and releases
- Wrap-up
Lala, personalized to you, gives a hint when you ask and reviews your design when you are ready.
What do interviewers look for?
In any mobile system design round.
- Clarifies the requirements before drawing anything
- Uses a few numbers that actually change the design
- Draws a clear path from the client to storage
- Picks storage and caching with reasons, not by habit
- Explains what breaks first under load and how to fix it
- States trade-offs openly instead of claiming a perfect design
Questions people ask about this interview question
- Which design type is this question?
- It is a mobile system question. You design a fitness tracker app like strava and explain your choices the way you would in an interview.
- Is this question asked at entry level?
- It is marked Medium. Entry-level engineers can practise it, but it expects you to reason about requirements and trade-offs, not only list components.
- What should I cover first?
- Start with the requirements: what the system must do, how well it must do it and which numbers change the design. Agree on scope with the interviewer before you design anything.
- Can I practise it for free?
- It is a premium question. Sign up and unlock it once for 10 credits; it then stays unlocked. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.
Related questions
Updated · Written by the SevyDevy team