Design a crash reporting SDK like crashlytics
PremiumMobile systemMedium
- Signal handlers
- Async signal safe
- Symbolication
Quick answer
This mobile system interview question asks you to design a crash reporting SDK like crashlytics. 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 crash reporting SDK like Crashlytics for iOS and Android apps. It catches crashes and hangs, records what led up to them, and sends reports that turn into readable stack traces. The hard parts are capturing a report inside a dying process, crashes that the app cannot catch at all, and crash loops at startup.
The ingestion and grouping service is a given. Design the SDK and the build steps it needs.
What must a crash reporting SDK like crashlytics do?
- Catch crashes: Uncaught Objective-C, Java and Kotlin exceptions, Swift runtime traps and native crashes (bad memory access, aborts).
- Hangs and ANRs: Detect a main thread blocked for 2 seconds on iOS and Android ANRs (input not handled for 5 seconds).
How well must it do it?
- Safe handler: The crash handler never deadlocks or corrupts the report, even with a broken heap.
- No impact: Under 20 ms added to app start and under 1% CPU at run time.
What scale should you design for?
Use these numbers in your estimates.
The scale numbers unlock with this questionUnlock
Key concepts
- Signal handlers
- Async signal safe
- Symbolication
- ANR detection
- dSYM
- R8 mapping files
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 crash reporting SDK like crashlytics 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.
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Updated · Written by the SevyDevy team