(Senior) Backend Engineer - Banking (f/m/x)

About lemon.markets 🍋 We enable anyone to be an investor. Our mission is to grow investing opportunities for all European customers and businesses. By empowering FinTechs, banks, and wealth managers to offer investment products, we help create financial well-being for their customers. lemon.markets is a Brokerage-as-a-Service platform: simple digital access to capital markets through a single API. Our API-first infrastructure abstracts brokerage complexity with a well-documented API, a self-service customer operations portal, and a clear regulatory framework, so partners can launch customer-centric, compliant products in weeks, not months. As part of the dwpbank group, we’re adding a layer of resources and expertise to benefit from, while continuing to operate as an independent fintech with our own team, product, and start-up identity under the dwpbank umbrella. Your Mission: As a Senior Backend Engineer in the Banking domain at lemon.markets, you will design and own reliable, scalable backend services that keep money moving safely and efficiently for our partners and their customers. Within this domain, you will build and operate systems across settlements, payments, and ledger accuracy, ensuring execution with partners is correct, cash flows are fast and reliable, and reconciliation reflects reality. You will take end-to-end ownership in a cross-functional team, helping ensure operational compliance tasks meet regulatory and contractual SLAs while tracking partner-visible incidents that could affect trust and assets under custody. Our Tech Stack is Python, FastAPI, AWS and Postgres. You will have a significant impact on the development of our core Platform & Systems, and therefore on architectural decisions and the business itself. Working alongside a cross-functional team of experts, you will help build the banking infrastructure that enables accurate settlements, reliable payments, resilient ledger and reconciliation systems, and trusted partner operations for the next 100 million retail investors in Europe. About you: You write well-structured, maintainable and well-tested code in at least one modern programming language, such as Python , Go, Java, Ruby, JavaScript or TypeScript. We’re technology agnostic, so Python experience isn’t required, but you should be excited to learn it. You have experience in designing and implementing highly scalable architecture and reliable REST APIs and bring the desire to make them world-class. You’ve gained good experience with software in a cloud environment (AWS, GCP, Azure) and the architectural patterns for this environment. You have a good understanding of any of these document-based or relational database technology such as MySQL/ PostgreSQL . You know how to write high-quality code that is understandable, maintainable and well tested, and can guide other engineers to do the same via code reviews. You have a track record of designing, building and operating reliable and scalable backend systems as