(Senior) Backend Engineer - Investing (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 Investing domain at lemon.markets, you will design and own reliable, scalable backend services for our brokerage API platform, helping make investing accessible to more people across Europe. Within this domain, you will build and operate systems across the full securities lifecycle: instruments and market data, orders and trades, portfolios and positions, taxes, clearing and settlements, corporate actions, and reporting. You will take ownership end to end in a cross-functional team, working with internal and external partners to deliver secure, resilient systems for customer and institutional order workflows, including batch trading, transfers, transaction reporting, and market abuse screening. Our Tech Stack is Python, FastAPI, AWS and Postgres. You will have a significant impact on the development of our core Platform & Systems - and thereby architectural decisions, as well as on the business itself. Work alongside a cross-functional team of experts, and together we will leverage your previous experiences to build the investment infrastructure 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 part of