Staff Product Security Engineer, Reviews

🚀 We’re on a mission to make money work for everyone. We’re waving goodbye to the complicated and confusing ways of traditional banking. After starting as a prepaid card, our product offering has grown a lot in the last 10 years in the UK. As well as personal and business bank accounts, we offer joint accounts, accounts for 16-17 year olds, a free kids account and credit cards in the UK, with more exciting things to come beyond. Our UK customers can also save, invest and combine their pensions with us.  With our hot coral cards and get-paid-early feature, combined with financial education on social media and our award winning customer service, we have a long history of creating magical moments for our customers! We’re not about selling products - we want to solve problems and change lives through Monzo ❤️ ----------------------------------------------------------------------------------------------------------------------------------   📍Barcelona, Spain | 💰 Base salary for this role is depending on experience + benefits | Hybrid model: 3 days a week in the office About our Engineering Teams: We have over 650 engineers across Monzo who design and build our in-house banking platform. We have big ambitions for the future, and technology plays a big role in creating a bank our customers want, so engineers at Monzo collaborate across disciplines to solve interesting challenges throughout the company. These range from the products our customers use everyday to underlying infrastructure, security, payments and finance, customer operations, financial crime, and data, to name just a few areas. As a bank, there is scope for impact across a huge number of opportunities. We contribute to open source software as much as possible. Our blog is a good place to learn even more about what we do! What you’ll be working on:  We rely heavily on the following tools and technologies: * Go to write our application code (there’s an excellent interactive Go tutorial here) * Cassandra for most persistent data storage * Kafka for our asynchronous message queue * Envoy Proxy for RPC * Kubernetes and Docker to schedule and run our services  * AWS for most of our infrastructure * React for internal web dashboards * We also have two physical datacenter sites with actual cables to connect to various third parties Your day-to-day    This role is all about collaborating across disciplines to test hypotheses and make a difference to customers. As a product backend engineer you’ll work in a squad alongside product managers, marketers, user researchers, designers, mobile engineers, web engineers, data analysts, business analysts, writers and more!  Together you’ll build and support a particular part of Monzo. Our product squads belong to our wider collectives (a word we use to describe self-governing business units of ~100 people). They are; Money, Borrowing, Fincrime, Customer Operations, Platform, Personal Banking & Business Banking. They’re all looking for additional Backend Engineers right now, we do a standard interview process across all our collectives and at the end we will find the best match for you based on your skills, experience, preferences and aligning with the business need!  Our backend engineers have a variety of different backgrounds. As long as you enjoy learning new things, we’d love to talk to you. We do not ask for formal qualifications or degree requirements for any of our engineering roles. You should apply if: * you have strong experience working on the backend of a technology product * you want to be involved in building a product that you (and the people you know) use every day * you have a product mindset: you care about customer outcomes and you want to make data-informed decisions * you’re comfortable working in a team that deals with ambiguity * you’re interested in distributed systems and writing resilient software * you have some experience with strongly-typed languages (Go, Java, C, Scala etc.). * you think you’d enjoy the kind of work we’re doing We're on the look out for L60 Engineers at the moment, you can read more in our Engineering Progression Framework we are also hiring on L40 & L50, our interview process will determine your levelling.  The Interview Process: Our interview process involves three main stages:  1. Initial Call  2. Take home task or pair coding exercise  3. Final interview including a system design and a behavioural interview  One of our engineers has written a detailed blog on their experience through this process, for extra details, hints and tips please see here. What’s in it for you: 💰Base salary range for this role is depending on experience + equity + stock options & benefits  📍Barcelona, Spain ⏰ We offer flexible working hours and trust you to work enough hours to do your job well, at times that suit you and your team. 📚Learning budget of €1,200 a year for books, training courses and conferences #LI-JS1 ---------------------------------------------------------------------------------------------------------------------------------- Equal opportunities for everyone Diversity and inclusion are a priority for us and we’re making sure we have lots of support for all of our people to grow at Monzo. At Monzo, we’re embracing diversity by fostering an inclusive environment for all people to do the best work of their lives with us. This is integral to our mission of making money work for everyone. You can read more in our blog, 2026 Diversity and Inclusion Report and 2025 Gender Pay Gap Report. We’re an equal opportunity employer. All applicants will be considered for employment without attention to age, ethnicity, religion, sex, sexual orientation, gender identity, family or parental status, national origin, or veteran, neurodiversity or disability status. If you have a preferred name, please use it to apply. We don't need full or birth names at application stage 😊

About the Role We’re looking for a Staff Data Scientist to shape the future of our marketplace through advanced analytics, experimentation, and machine learning. You’ll define the technical direction of data science initiatives, influence product strategy, and mentor other data scientists to elevate our analytical standards and impact. As a Senior Technical Leader, you’ll partner closely with Product, Engineering, and Operations teams to turn data into decisions that improve reliability, growth, and user experience across markets. What You’ll Do - Lead data science initiatives with company-wide impact — from experimentation frameworks to ML systems and causal inference methods - Define best practices and standards for experimentation, modelling, and analytical excellence across teams - Partner with Product and Engineering leadership to identify and prioritise high-leverage opportunities - Develop and deploy scalable models and data products that drive measurable business outcomes - Mentor and coach other data scientists and analysts, helping them deliver higher-impact work - Communicate insights and recommendations to senior leadership, influencing product and growth strategy - Contribute to Heetch’s data platform evolution, ensuring data quality, reliability, and efficiency at scale You’ll Thrive In This Role If You - Have a deep understanding of statistics, experimentation, and causal inference, and know how to apply them pragmatically - Are fluent in Python, SQL, and modern data/ML tooling - Have experience bringing ML models into production and measuring their long-term business impact - Are skilled at translating complex technical findings into actionable business insights - Are a collaborative leader who mentors peers and sets high standards for analytical rigor and impact - Have 7+ years of experience in data science, ideally with 2–3 years in a Staff-level or tech-lead capacity Nice to Have - Experience in marketplace or pricing systems (supply–demand modelling, matching, or fraud detection) - Experience leading data science guilds, chapters, or communities of practice - Familiarity with MLOps, feature stores, or causal inference frameworks