How to ace the Mobile Engineering interview at Cash App

With Mackenzie Engel, Senior Tech Recruiter

We know interviewing can be nerve-wracking, but it doesn’t have to be. It should spark great conversation and be an opportunity for you to interview our team, too.

You’re probably wondering what it’s like to interview for a Mobile Engineering role at Block. To take some of the mystery out of interviewing, we sat down with Mackenzie Engel, a Senior Recruiter on the team, to walk you through the process and share some tips on how to ace it.

Meet your guide

Mackenzie is the lead recruiter for the Mobile Engineering team at Block and has helped build the interview processes you’ll be going through here. In her role, she acts as a coach, guiding candidates through the stages of the interview loop. She provides support at each stage of the process so candidates feel well-informed and can focus on preparing to put their best foot forward.

“I joined Block because I was blown away by my own interviews and the people I met with,” Mackenzie says. “I could tell that each interviewer genuinely cared about my experience in the interview process and was invested in our conversations. I was also excited to join a Fintech company that believes in economic empowerment; Block’s purpose resonates with what matters to me at this point in my career.”

Mackenzie is always excited to partner with the Mobile team because they’re empathetic  and easy to work with, and they play a huge role across our product lineup. “The majority of our products are truly mobile-first, so mobile is a big part of everything we do, which makes hiring for this team even more fun,” she says. 

Mobile at Block is focused on building a high-performing team and creating an environment where people from different backgrounds can succeed. “The mobile engineering leaders do a great job of recognizing the role they play in setting their team up for success, and consistently challenge themselves, and each other, to be better. They take a human-centric approach to managing, with a focus on fostering environments of inclusivity and supporting their teams to meet our high bar of engineering excellence,” Mackenzie says.

About the Mobile team

Our Mobile teams build the products, features, and frameworks that power Block’s Cash App and Square products. From building brand-new products to iterating on existing ones and working on systems that enable other engineers to do their best work, there is never a dull moment as a Mobile Engineer at Block. “The team is always at the bleeding edge of newer mobile technologies, and often are the ones creating them themselves, which you can see exemplified in our open source work,” Mackenzie explains.

The Mobile Engineering team embodies Block’s Give It Soul operating principle. They want creativity to be a competitive advantage for Block and to make users excited and delighted to use our products. To do that, they collaborate with the Design and Product teams and always push themselves to think beyond the screen to the customer experience.

On the technical side, the team works across Android using Kotlin and iOS using Swift. We also test out newer technologies often, so things are constantly evolving.

As the Mobile team grows, it’s looking for folks excited about Block’s purpose of economic empowerment and passionate about mobile development. “We’ve built a great culture here, and we’re looking to hire folks who will continue to elevate it with their unique perspectives,” Mackenzie says. “So if you’re a mobile developer and are passionate about what you do—please reach out!”

The interview process: What to expect

After your initial call with your recruiter, the Mobile interview process involves 2-3 rounds.  

The first round is our technical screen stage. At this stage, you’ll have a choice between two options:

• Option 1: A mobile take-home project, where you’ll be given the requirements to develop a lightweight mobile application. We typically encourage you to spend no more than 3-4 hours on this, but you’ll be given a week to complete it. Once you send it back, we’ll pass it along to our mobile engineers to review. In this exercise, we’re looking for sound architectural decisions, well-crafted UI, thoughtful testing, and whether you followed the specifications and requirements listed in the prompt.

• Option 2: A 60-minute pair programming interview, during which you’ll work virtually with an engineer using CoderPad to solve a multi-part problem. The questions are not mobile-specific, but they’re designed so that any engineer can complete them, and you should feel free to use the language you’re most comfortable with. In this portion of the process, we’ll be evaluating your collaboration skills, code quality, and problem-solving approach.

The second round of the interview process is a Hiring Manager screen. This is an opportunity for you to learn more about the team, and for your hiring manager to learn about your background and what you’re looking for next. The goal is for both of you to determine if there is alignment between your skills, your interests, and the role itself. This round may be moved to the virtual onsite stage on a case by case basis.

The third round of interviews is the virtual on-site. You’ll complete 2 coding and 2-3 behavioral interviews during this phase, depending on the seniority of the role. If you went with the Pair Programming interview for the first round, the coding portion of the on-site will be very similar. If you went with the Take-Home Project, the coding portion during the on-site will focus on adding features and functionality to your project in pair-programming style interviews. The behavioral interviews will focus on your past cross-functional and project management experience, your mobile system design and architecture knowledge, and, potentially, your ability to act in a leadership capacity and drive technical decisions while mentoring other engineers.

Advice from the recruiter: How to ace your interview

To knock your interviews out of the park, Mackenzie recommends being prepared to share why you’re excited about Block, and what drew you to a particular product (e.g. Cash App or Square), from a business and/or technical perspective. Mackenzie also recommends highlighting your passions as a way to stand out. “Folks who are passionate about what they do leave an impression, so if you’re genuinely excited about Mobile or Fintech, or if Block is your dream company, tell us that,” she says.

For any of the pair-programming style technical interviews, remember to ask clarifying questions before you start coding and to share your thought process every step of the way. Explain the decisions or trade-offs you’re making and why. “The better your interviewer can follow along, the easier it will be for them to help if you get stuck,” Mackenzie says. “Part of their job is to set you up for success, whether that’s providing hints or jumping into the code with you to problem solve.” For the behavioral interviews, she encourages you to come prepared with several stories that highlight impactful projects that you’re proud of. “Don’t be shy about acknowledging your personal contributions. We love teamwork, but we also want to understand your particular level of impact and ownership.”

Mackenzie’s final words of advice for crushing your mobile interview? “Leverage your recruiter! I am rooting for you. I care deeply about my candidates and want to see them succeed. Ask me anything and I will answer as transparently as possible,” she says.

Ready to build an economy that works for everyone? Check out open roles.