Demystifying the Senior Staff+ Engineering interview process

Ask a handful of companies to define the scope and impact of a Senior Staff+ Engineer, and you’ll likely get many different answers. Titles across the tech industry aren’t standardised, often leading to confusion during the application and interview process.

At Monzo, we aim for transparency by sharing our Progression Framework to ensure everyone is aligned with our leveling. Before interviewing, we highly recommend reviewing this document to better understand expectations for each level. 

This post explains what you should expect from each of our interviewing stages and how to prepare.

We have six interviews across four stages:

All interview stages are with engineers or engineering managers and directors who work at Monzo and develop systems or manage engineers on a day to day basis. Interviews will typically contain a tenured engineer but may also contain observers who are learning to become interviewers themselves. 

Each interview will also have time dedicated for you to ask questions about working at Monzo and working on a specific team. Interviewing is a two-way street so feel free to ask engineers on this call how we do things you discuss at Monzo. We love talking about the work we do and our tech stack.

Let’s break each of these stages down!

If we think you’re a match for the role, one of our recruiters will schedule a call to learn more about you, answer your questions, and guide you through the process. We’ll always share the outcome or next steps so you’re not left hanging.

You’ll also learn what Monzo’s mission is, how Senior Staff+ engineers work towards that mission and how you can play a crucial part in us achieving it.

The one hour initial call is geared towards understanding your background and experience and complexity of the technical projects you’ve led. We will have already read your CV so this is your opportunity to dive deeper into your contributions.

We like to focus on projects you’ve worked on recently as those will be most fresh on your mind. We want to get into the details of how the project manifested, how it was implemented, what trade-offs were made, what would you do differently in hindsight, and more.

It should feel more like a conversation than a scripted question set, but we’ll usually cover:

You’ll be speaking to fellow engineers (maybe even your future team members). We like to hear about the technical details such as data structures, language choices, performance/reliability trade-offs and security considerations. 

Spend time getting up to speed on a recent project you’ve worked on (ideally a project where you’ve had significant input across multiple teams with a high level of complexity). Focus your effort in helping us understand where you as an individual contributed to the project. 

You shouldn’t need to prepare anything beforehand. We won’t expect you to do any whiteboarding or show off any code but will ask you to explain your project.

The aim of this stage is to gauge your coding ability and how you get computers to do your bidding. 

You can choose if you’d like to:

The process is the same for what we do for all Backend Engineers. You can find preparation tips in our blog post on Demystifying the Backend Engineering interview process

The systems design interview gives us insight in building scalable, reliable and fault-tolerant systems. You work with a Monzo engineer to design a system to solve a large technical problem (the problem will be a hypothetical, non-Monzo related problem). We’ll be integrating systems such as databases, queues, and more. You’ll be making trade-offs and we’ll be probing to understand what these are. We’ll be working with a collaborative sketching tool like Excalidraw

The most important thing in this session is to maintain a shared understanding with your design. By the end of the interview, we should be able to go away and describe your proposed solution to others. The session for Senior Staff+ roles is slightly longer to allow us to go deeper on the scalability and testing and security of your proposed system. 

You can find a full list of preparation tips in our blog post on Demystifying the Backend Engineering interview process. 

It’s tempting to drop mentions of buzzword technologies that promise infinite scalability or take care of all consistency and availability. We will probe deeper on why you believe such a component makes sense. 

We often see folks implement textbook solutions. Instead we’re more interested in how you reason about designing systems from first principles.

This is where we talk through your experience as part of a team, working with other engineers, breaking down complex work and delivering on projects. A core part of our day to day is working alongside our team and the broader company to deliver to large scale goals incrementally and at scale.

You’ll have a one hour video call with two interviewers, who might be senior engineers or engineering managers from any part of the business. We'll cover 4 key areas around exploring your approach to topics like communication, learning, working in a team, and delivering projects. Working at Monzo involves incrementally delivering projects (large and small) at pace, tackling complexity along the way so the collaboration and project delivery skills we explore in this stage are just as important as technical excellence.

Similar to the initial call, we’ll go in depth about situations you may have encountered, your thought process for delivering software and your methodology to navigate the complex world of humans and stakeholders.

We want to see how you work with others. If you were influential in rallying a particular effort or levelling up other engineers, there will be opportunity to touch on these points. 

It’s important to distinguish and focus on the things you led personally as opposed to efforts of others that you were involved in.

This interview is designed to understand how you have previously been able to proactively identify a problem or an opportunity, and dig into how you have worked to influence a sufficiently broad group of stakeholders that there is value in tackling the problem, and how you executed using your technical skills.

We will discuss the scope, ambiguity and ambition of your achievements, and what impact they have on your team / company. We will dive deep into areas where you needed to be persuaded to go down a different path. 

We want to understand how you think strategically. We want to understand how your achievements laddered up into something bigger 

Take some time to reflect on your past projects (if you have led a particular complex project or been a significant contributor to a project, these are good things to reflect on). Be sure to talk about the stakeholders involved and how everyone was kept aligned. Be clear on impact that has been delivered vs impact that has yet to land (maybe because the project has not yet shipped).

Focus on how you identify opportunities as a leader and convince a group of people to execute on your vision. Use your examples to showcase to us when this has worked well (or not so well, both can be interesting)

Once you’ve completed all your interviews, we’ll bring your interviewers together for a structured debrief to review feedback and make a decision. We look at every part of the interview process and take time to discuss your strengths, areas for development, and how your experience aligns with what we’re looking for.

Instead of a formal hiring committee, we use these collaborative debrief sessions to ensure a fair, balanced decision-making process. We also use them to challenge bias, align on values and behaviours, and continually improve the way we interview.

This approach not only helps us make the right hiring decisions, but also ensures we place you in the part of Monzo that best fits your skills, interests, and aspirations—somewhere you’ll enjoy the work, feel supported, and have the opportunity to grow and thrive.

If we feel like there’s a good fit, we’ll make an offer 🎉. We hope that you join us!

Throughout all of the interview stages, there’s some common tips to keep in mind

At Monzo building the best current account in the world. We're always on the look out for Backend Engineers, Staff Backend Engineers and Engineering Managers.