Senior Backend Engineer (Data serving)

About Pleo Messy spend management is tricky business. And tedious processes are a lose-lose situation for all involved, not just finance. At Pleo, we're changing that. We build spend solutions that make managing money seamless, empowering, and surprisingly effective for finance teams and employees alike - with a vision to help all businesses ‘go beyond’. The word ‘Pleo’ actually means ‘more than you’d expect’, and living by that mantra has been the secret to our success over the last 10 years. Now, we’re at a pivotal moment in our journey; every move we make has a direct impact on our 40,000+ customers, our business, and our collective success. We need people who take pride in uncovering customer needs, who turn complex problems into simple solutions, challenge the way things are done (respectfully), and always aim high. With great ambitions driving us forward, we can’t say we’ve got this whole thing figured out. And frankly, that’s half the fun! What we can say is that we’re a driven, progressive, and, importantly, a kind bunch of 850+ people from over 100 nationalities, all committed to delivering the future of business spending, together. Please note: applications will be open until Tuesday 13th October 2026 at 08.00 CEST. We will not review any application before the closing date so please use this time to submit a high quality application. About the role We're looking for a Senior Backend Engineer to join the Data Serving team that owns the production-grade boundary between Pleo's raw product data and everyone who consumes it, including internal product teams, AI agents, and customers directly accessing their own data. This Senior Backend Engineer role builds and owns that boundary: APIs and the low-latency serving layer underneath it. You will build customer-facing infrastructure where contract stability and latency are non-negotiable, and where the clean abstraction you maintain is what lets every downstream consumer trust the data without ever touching a raw source. Who you’ll be working with and reporting to You will report to our Senior Manager of Data & AI Products, and work closely with our Staff Data Platform Engineer, Data Engineers, Product Managers and others Engineers across the business. You'll also coordinate closely with the GenAI Platform and Data Infrastructure teams. What you’ll be doing As a Senior Backend Engineer, you will: Build and own the Data API boundary: delivering clean, versioned, and performant endpoints for internal dashboards, customer-facing features, and third-party tools (e.g., Fivetran connectors via incremental syncs and cursor pagination). Design and optimise the read models, indexes, and caching strategies in Postgres (and future OLAP stores) to guarantee low-latency query performance. Build reliable integrations with Pleo’s Kotlin-based product backend services to ensure the serving layer surfaces the correct data required for a customer facing feature. Own the reliability and performance of the services you build: monitoring, incident response, and SLOs appropriate to customer-facing infrastructure. Partner with Data Engineers to define clean contracts between the ingestion/aggregation layer and the serving DB, ensuring read patterns match storage schemas. Partner with the Authorization team to secure APIs using industry-standard authentication and authorization protocols. Build a near-real-time data aggregation service to collect and unify data across Pleo services. Design metadata, lineage, and governance capabilities that make the serving layer explainable, auditable, and trustworthy. Own access control and permission management services, including row and column-level data access with full audit trails. To put things into context, you can expect to work with the following tech stack: AWS (product side), GCP (data side), Docker, Kubernetes, BigQuery, PostgreSQL dbt, Kafka, Airflow, Python, Kotlin and more! What you bring You’ll thrive in this role if you have: Strong backend engineering experience building and owning reporting and analytics API services and serving-layer infrastructure. A mindset focusing on reliability, latency, and SLOs. Experience owning API boundary layers including clean endpoint design, versioning, contract stability, and ensuring downstream consumers are never exposed to raw data sources. Strong expertise designing performant read-heavy systems, including relational database optimisation, indexing strategies, materialised views, caching, and API performance tuning. Solid database fundamentals (SQL and non-SQL) and strong SQL querying skills, as well as deep expertise in Kafka. Deep experience with a JVM-based language (Pleo's product backend is Kotlin-based). AWS or GCP with Kubernetes experience. You must be familiar with configuring, deploying and operating containerised applications in a k8s environment. Experience working at the boundary between data systems and product backend services, with a real understanding of the operational differences between the two. The ability to move quickly and independently. This is a hands-on delivery role with clear scope, not an architecture or advisory engagement. Experience in fintech, payments, or other regulated product environments. Why is this role a good fit for you This role is a good fit for you if: You are passionate about building systems that serve other engineers. You understand what it means to design, build and maintain services with high performance, availability and reliability requirements. You have a very deep understanding of the data world and know how to bridge the gap between data and engineering. This role is not a good fit for you if: You need to operate within very large and structured teams with clear hierarchy. This role sits within a small and specialist team with a lot of autonomy. You do not wish to be responsible for services with high availability requirements. You will be held accountable for the quality and availability of those services alongside your team. You prefer to be handed over clearly defined scope of work. You will be expected to define and design the solutions as much as building them. How you’ll develop in this role In your first 6 months at Pleo, you will: Get deep into the current state: the upstream Kotlin services the serving layer will pull from, the internal consumers already waiting on the API (Data & AI Products, GenAI Platform), and any prototype serving logic that needs to be replaced or formalised. Ship the first production version of the Reporting API (a defined set of endpoints with agreed contracts, versioning, and SLOs) with at least one internal consumer live against it. Establish the access control, tenant isolation, and row/column-level security model for the API. You will have proven out low-latency query performance on Postgres, with clear metrics around reliability and SLOs, and established a clear architectural benchmark to understand when (or if) an OLAP layer would ever be necessary. Please note: We can hire on a remote, hybrid or in-person set-up in any of the locations listed on the advert but you will need to be physically based in the country of your choice with a valid right to work. We are unable to offer visa sponsorship for this role in any of the listed locations. Show me the benefits Your own Pleo card (no more out-of-pocket spending!) Lunch is on us for your work days - enjoy catered meals or receive a lunch allowance based on your local office Comprehensive private healthcare - depending on your location, coverage options include Vitality, Alan or Médis. 25 days of annual leave + public holidays (additional days may apply in select countries based on local standards). For our Team, we offer both hybrid and fully remote working options. We use MyndUp to give our employees access to free mental health and well-being support with great success so far Paid parental leave - we want to make sure that we're supportive of families and help you feel that you don't have to compromise your family due to work The interview process We want to ensure you are set-up for success and understand what will be expected of you. If your application is successful, our interview process is as follows: Intro call: A 30-minute chat with our Talent Partner to discuss the role and your background. Core skills test: An async AI-assisted programming test to assess your coding fundamentals. Hiring Manager interview: A 60-minute chat deep diving into your experience. Pleo Challenge: A 75-minute system design interview focusing on your architecture, infrastructure and problem-solving skills. Transparency is important to us so we also wanted to share some insights about what we’re looking for in applications to ensure you can set yourself up for success! With this in mind, we want to help you understand what we really care about when reviewing your application: We receive a lot of CVs, and many of them are AI-generated. We love seeing people leverage AI - it’s a big focus for us internally too- but without human intervention, these CVs can sometimes become generic and fail to show a candidate in the best light. What we're really looking for is the specific details of real impact that only you - not AI - know from your previous experience. A top tip from us is to use the “Achieved X, as measured by Y, by doing Z” formula (credit: Laszlo Bock, ~2014) to give a really clear picture of what you’ve worked on. A final note: including links to your previous companies' websites is a huge help and allows us to truly understand your background. Every single application we receive is reviewed by a human (yes, hundreds of them) because we believe that candidates' efforts should be matched by an equal level of human care. This means that we expect a similar level of attention put into your application. Read and answer the application questions carefully, they make a huge difference in our decision-making process. This role focuses heavily on building services for internal / external users consumption. It is absolutely critical to have extensive API design and development experience, expertise in OLAP systems and to be able to work in Kotlin. Ensure your CV reflects clearly of the actual experience you have across those areas. About your application English first. Since it's our company language, please submit your application in English. You’ll be using it a lot if you join us. A fair look for everyone. Our talent team reads every single application to ensure the process is fair. To keep things running smoothly, we only accept applications through our system—our support team can’t pass on calls or emails. Diversity drives us. We can only reach our goals if our team reflects the world around us. That starts with you hitting apply, even if you don't tick every single box. We encourage people from all backgrounds and experiences to join us. Interview at your best. We want you to feel comfortable throughout the process. If you have any accessibility requirements or need a specific format, email ----- We’ll design a process that works for you. Your data is safe. When you apply, we process your personal data as a data processor. For more information on how Pleo processes personal data, read our Privacy Policy here. Applying for multiple roles? Nothing is stopping you, and we assess every role independently. However, we do look for alignment, so make sure you can explain why your interest and experience are right for each specific role. Reapplying. If you’re applying for the same role again, please wait six months from your last decision before hitting submit. Find Jobs in United Kingdom on Arbeitnow