Example scenarios:

• "Design a mobile framework for processing peer-to-peer payments that can securely queue transactions when offline and reconcile them with the backend once a stable network connection is re-established."
• "Design the architecture for a modular, white-labeled point-of-sale application where third-party developers can build and plug in their own custom payment-processing UIs."

Behavioral & Leadership

Square looks for engineers who are humble, highly collaborative, and deeply empathetic toward both their teammates and the merchants who use their software. This interview explores your past experiences to understand how you handle adversity, drive technical alignment, and contribute to a healthy engineering culture.

Be ready to go over:

• Conflict Resolution – Navigating technical disagreements with peers or stakeholders using data and constructive compromise.
• Ownership & Initiative – Identifying systemic code smells, process bottlenecks, or product gaps and driving the solution to completion.
• Adaptability – Responding to shifting product priorities, tight deadlines, and technical constraints without sacrificing quality.

Example scenarios:

• "Tell me about a time you inherited a poorly written legacy codebase. How did you balance the need to deliver new features with your desire to refactor and clean up the technical debt?"
• "Describe a situation where a critical bug you wrote bypassed QA and made it to production. How did you handle the incident, coordinate the hotfix, and what steps did you take to prevent it from happening again?"

On a day-to-day basis, a Mobile Engineer at Square is responsible for delivering high-impact features that directly affect how merchants interact with the platform. You will write clean, well-tested Swift or Kotlin code, participate in comprehensive code reviews, and contribute to architectural discussions that shape the future of the mobile platforms.

Collaboration is a core component of the role. You will work closely with cross-functional partners, including Product Managers, Product Designers, QA Engineers, and Backend Engineers. Together, you will define API contracts, design intuitive user experiences, and ensure that new features are rolled out safely using robust feature flagging and phased release strategies.

Additionally, you will play an active role in maintaining the health of the codebase. This includes refactoring legacy code, upgrading build tooling, optimizing application performance, and ensuring the apps meet high standards of accessibility and localization. You will also mentor junior engineers, participate in hiring, and help foster an inclusive, high-performing engineering culture.

To be competitive for a Mobile Engineer position at Square, you must demonstrate a strong track record of shipping and maintaining high-quality native mobile applications in a production environment.

• Must-have skills:

  • Deep proficiency in either Android development (Kotlin, Java, Jetpack Compose) or iOS development (Swift, Objective-C, SwiftUI).
  • Strong understanding of mobile architecture patterns (MVVM, MVI, Clean Architecture) and design principles.
  • Proven experience writing comprehensive unit, integration, and UI tests.
  • Solid grasp of multi-threading, memory management, and mobile performance profiling tools.
  • Experience consuming RESTful or GraphQL APIs and managing local data persistence.

• Nice-to-have skills:

  • Experience working on offline-first applications or payment-processing systems.
  • Familiarity with mobile CI/CD pipelines, automated testing infrastructure, and app store deployment processes.
  • Contributions to open-source mobile libraries or active participation in the broader mobile developer community.
  • Experience with multi-module codebases and dependency injection frameworks (e.g., Dagger/Hilt on Android, or custom DI containers on iOS).

Q: Can I choose between the take-home project and the live coding screen? A: Yes, Square typically offers candidates a choice for the initial technical screen. You can either complete an asynchronous take-home project or participate in a live, 60-minute programming session. If you choose the take-home, your on-site will focus on extending that codebase; if you choose the live screen, your on-site will consist of traditional pair-programming rounds.

Q: How strictly is the time limit on the take-home project enforced? A: While the prompt states you should spend 5 to 8 hours, the submission is graded against very high production standards. Reviewers look for clean architecture, robust error handling, and solid test coverage. It is highly recommended to prioritize quality and completeness over strict adherence to the lower end of the time estimate, or ensure any shortcuts are thoroughly documented in your README.

Q: What is the culture like for Mobile Engineers at Square? A: The engineering culture at Square is highly collaborative, pragmatic, and user-focused. Teams operate with a high degree of autonomy and are deeply committed to maintaining code quality and engineering excellence. There is a strong emphasis on writing design docs, conducting thorough peer reviews, and continuously learning from post-mortems.

Q: Does Square support remote work for Mobile Engineers? A: Square (under its parent company Block) has a highly flexible, remote-friendly work policy. Many mobile engineering teams operate in a fully remote or hybrid model, though specific expectations can vary depending on the team, project requirements, and your geographic location.

• Treat your take-home like production code: Do not cut corners on architecture, error handling, or testing. If you run out of time to implement a specific optimization, write a highly detailed README explaining exactly what you would have done differently with more time, detailing your architectural choices and testing strategy.

• Communicate constantly during live sessions: Whether you are doing the live coding screen or the on-site code extensions, treat your interviewer as a collaborator. Verbalize your thought process, explain the trade-offs of your approach, and ask for feedback before writing large blocks of code.

• Master your platform's modern UI frameworks: Square heavily utilizes modern declarative UI frameworks. Ensure you are highly comfortable building layouts, managing state, and handling animations using Jetpack Compose (for Android) or SwiftUI (for iOS).

• Be prepared for rigorous code reviews: During the live extension rounds, your interviewer will review your code in real-time. Be receptive to feedback, avoid becoming defensive when your code is questioned, and demonstrate your ability to adapt your solution based on constructive input.

A Mobile Engineer role at Square offers a unique opportunity to work on highly complex, large-scale mobile applications that directly impact the livelihoods of millions of merchants worldwide. The interview process is designed to be a practical reflection of this day-to-day work, focusing on clean architecture, robust testing, collaborative problem-solving, and system design. While the technical bar is exceptionally high—particularly regarding the execution of the take-home project—focused, methodical preparation can significantly increase your chances of success.

To stand out, dedicate time to mastering clean architecture patterns, practicing live coding extensions, and refining your ability to design resilient, offline-first mobile systems. Approach every interview round with a collaborative, humble mindset, treating your interviewers as peers and demonstrating deep empathy for the end user.

The compensation data above reflects the competitive market rates for mobile engineering talent at Square. Your final offer package will be determined by your performance throughout the interview loop, your depth of mobile expertise, and the level of the role you are targeting. To gain deeper insights into specific interview questions, company culture, and detailed salary breakdowns shared by recent candidates, explore the comprehensive resources available on Dataford. With the right preparation, you can confidently navigate the loop and secure your next role at Square.