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What the Round Looks Like at Each Company
On This Page
- Confirm three things before the interview
- Prepare for three types of discussion
A product feature
A library or SDK
A previous project
- Use company information carefully
Product-based practice examples
- A design interview is not the whole hiring process
- Adjust your answer to the confirmed scope
- Prepare when details are still unavailable
Practice questions
Takeaway
The title “mobile system design interview” does not describe one fixed format. Two teams at the same company may ask different kinds of questions. The time, role, and interviewer can also change what you need to explain.
Use company information to guide your preparation, but confirm the format for your position. Do not assume that a question reported by another candidate will be your question too.
1. Confirm three things before the interview
Available time. Ask how much time is available for the design discussion. A 60-minute session may also include introductions, questions about your experience, and time for your questions.
Scope. Ask whether you will design the mobile app, the app and API, or the complete system. An API is the set of requests and responses used to communicate with the server.
Type of question. Ask whether the session covers a product feature, a reusable library, or a project you previously built.
You can send this short message:
“Could you confirm the design portion's duration and scope? Will I design a mobile feature or library, discuss a previous project, or include backend components? Which drawing or coding tools should I prepare?”
These questions help you choose suitable practice exercises. They do not ask the recruiter to reveal the interview question.
2. Prepare for three types of discussion
A product feature
Examples include a chat screen, a news feed, an order tracker, and an offline reading feature.
Start with what the user needs. Then explain the screen's states, saved data, network requests, and failure behavior.
For an order tracker, discuss more than drawing a map. What happens when the location is old? What does the user see when the connection is lost? How does the app get the current order state after reopening?
A library or SDK
A library is reusable code used by other parts of an application. An SDK, or software development kit, provides tools and interfaces that help developers add a capability.
Examples include an image loader, file uploader, analytics SDK, or remote-configuration client.
These questions may have little or no user interface. Explain how another developer calls the component, how it reports results and errors, and what happens when several callers use it at once.
For an image loader, useful questions include:
- How does a caller request an image of a particular size?
- Can two callers share one download?
- What happens when one caller cancels?
- How much memory can the component use?
- How does it avoid returning an old image to a reused list row?
A previous project
You may be asked to explain a real system you helped build. Prepare the requirements, your contribution, important decisions, and one failure you investigated.
Use accurate numbers where you know them. If a value is an estimate, say so. Explain which decisions you made and which were made by other people.
A useful structure is: problem, design, your work, result, and what you would change now. Prepare a short overview and a more detailed explanation.
3. Use company information carefully
Prefer current material from the employer or recruiting team. Candidate reports can suggest topics to practice, but they may describe a different team, level, location, or hiring period.
For example, Amazon's software-development preparation page covers several technical topics and tells candidates to ask their recruiting contact which subjects are likely to be discussed. It is not a promise that every mobile position uses the same design interview. Amazon interview preparation
Uber provides interview preparation resources, including an engineering guide. Use the resources for your role and confirm how they apply to your scheduled session. Uber interview preparation
For Meta, Google, DoorDash, Lyft, Snap, and other employers, ask for the preparation material associated with your position. Do not replace that information with a general claim such as “this company always asks client-only questions.”
Product-based practice examples
The table below suggests exercises based on product behavior. These are practice choices, not claims about the questions each company asks.
| Product example | Useful exercise | Questions to examine |
|---|---|---|
| Feeds and messaging, such as Meta, Reddit, or LinkedIn products | A feed or conversation screen | What is saved? How are new items loaded? How are pending actions restored? |
| Transportation and delivery, such as Uber, Lyft, or DoorDash products | Order acceptance and tracking | Who confirms assignment? How old is the location? What happens after a timeout? |
| Media-heavy products, such as Snap or TikTok | Image loading or video upload | How is memory limited? Can an upload resume after interruption? |
| Music playback, such as Spotify | Offline downloads and playback | Which files are available? What happens when storage is low? |
| Shopping and delivery, such as Instacart, Flipkart, Swiggy, or Zomato | Cart and checkout | Can prices change? How does the app check an uncertain order result? |
| Financial products, such as Robinhood or CRED | Current data and transaction status | How is old data identified? Which results require server confirmation? |
Do not assume that a broad company name gives enough detail to choose one exercise. A company may hire for many products and platform teams. The job description and confirmed interview scope are more useful than the name alone.
4. A design interview is not the whole hiring process
An interview round is one session. An interview loop means the full set of sessions used in the hiring process.
The process may include coding, design, mobile platform questions, previous-project discussions, and behavioral questions. Confirm both the overall process and the content of the design session.
Some roles include a practical coding exercise. You may need to produce working code, not only draw an architecture. Ask what language, framework, environment, and tests are expected. Do not assume this format based only on a country or company.
If you receive a screen sketch, use it to clarify the visible behavior. It does not explain where data is saved, how requests are retried, or what happens offline. You still need to design those parts.
5. Adjust your answer to the confirmed scope
The same order-tracking example can lead to different discussions.
For a client-only question, explain screen state, local records, network calls, and recovery. Ask what the existing service guarantees.
For client and API design, also define the needed requests, responses, errors, and retry rules. For example, how can the app check whether an acceptance succeeded after losing the reply?
For a complete-system question, include the relevant backend components and explain how they enforce shared rules. For example, two drivers must not both receive the same exclusive assignment.
If the interviewer changes the scope, acknowledge the change and adjust the design. Do not continue with the original boundary without discussing the new requirement.
6. Prepare when details are still unavailable
Practice one product feature and one reusable component. Also prepare one previous project you can explain accurately.
Use the same basic method for design practice:
- Clarify the required behavior and scope.
- Describe the data and communication rules.
- Explain the main components and one complete flow.
- Examine an important technical problem in detail.
- Explain recovery, testing, and release considerations.
Practice drawing while speaking. Use short component labels and explain what each arrow means. A diagram should help the listener follow the behavior, not require them to guess it.
Practice questions
1. Another candidate says a company asked only about the mobile client. Should you assume the same scope?
<details> <summary>Show answer</summary>No. Their report may concern a different role or team. Confirm your scope with the recruiter and clarify it again when the design question begins.
</details>2. Why should you practice a library question as well as a screen-based feature?
<details> <summary>Show answer</summary>A library question focuses on how other code uses the component, including interfaces, errors, cancellation, and simultaneous callers. Preparing only screens may leave these topics unexplained.
</details>3. Does a screen sketch provide a complete design specification?
<details> <summary>Show answer</summary>No. It shows some visible behavior. You still need to clarify loading, errors, saved data, network communication, and recovery after interruption.
</details>Takeaway
Confirm the time, scope, and question type for your position. Use company products and published guidance to choose useful practice, not to predict an exact interview question.
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On This Page
- Confirm three things before the interview
- Prepare for three types of discussion
A product feature
A library or SDK
A previous project
- Use company information carefully
Product-based practice examples
- A design interview is not the whole hiring process
- Adjust your answer to the confirmed scope
- Prepare when details are still unavailable
Practice questions
Takeaway