Design a podcast app with offline downloads
PremiumMobile systemEasy
- Background downloads
- Background audio playback
- MediaSession
Quick answer
This mobile system interview question asks you to design a podcast app with offline downloads. 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 podcast app with offline downloads for iOS and Android. It downloads new episodes of followed shows in the background, plays them with the screen locked and remembers where the user stopped on every device. The hard parts are background download and playback rules on each OS, storage limits and audio interruptions such as phone calls.
What must a podcast app with offline downloads do?
- Auto-download: New episodes of followed shows download automatically on Wi-Fi, keeping up to 3 unplayed episodes per show.
- Offline play: Downloaded episodes play with no network; others stream.
How well must it do it?
- Reliable downloads: Downloads continue when the app is in the background and recover from network drops.
- Instant play: Downloaded episodes start in under 300 ms.
What scale should you design for?
Use these numbers in your estimates.
The scale numbers unlock with this questionUnlock
Key concepts
- Background downloads
- Background audio playback
- MediaSession
- Playback position sync
- Episode auto download
- Storage auto cleanup
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 podcast app with offline downloads and explain your choices the way you would in an interview.
- Is this question asked at entry level?
- It is marked Easy, so it suits engineers who are new to mobile system interviews. It is also a good warm-up before harder questions.
- 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.
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Updated · Written by the SevyDevy team