On behalf of our Client from the UK, Mobilunity is looking for Senior Python Engineer. You will join a small, international product team building an API-first financial technology platform that provides automated working capital solutions to UK small businesses. The role is highly impactful: you will design and build reliable, scalable services that directly influence how businesses access working capital. You’ll work in an environment with a high level of ownership, fast feedback loops, continuous deployment, and plenty of room to shape both the technology and the product. This is not a role where everything is already defined. You’ll work with real ambiguity, help shape evolving architecture, make decisions with incomplete information, and collaborate closely with domain experts and other engineers. What we’re looking for: We need an engineer who is comfortable taking ownership of complex problems, making pragmatic technical decisions, and working in a product environment where both the codebase and the domain are continuously evolving. The ideal candidate: thinks beyond implementation; is comfortable making decisions with incomplete information; understands scalability, reliability, security and business impact; has strong opinions about writing high-quality, typed Python; enjoys system design and building well-structured APIs; uses AI tools as a serious part of their engineering workflow while applying independent judgment; is comfortable working in a collaborative, low-ego environment. Responsibilities: Design, develop and maintain scalable backend services using Python. Design and implement domain services using Domain-Driven Design principles. Build performant, secure and fault-tolerant serverless solutions on AWS. Work closely with subject matter experts to translate business requirements into technical solutions. Participate in architectural and technology decisions at both project and company level. Design and maintain idiomatic APIs and service boundaries. Work with data modelling and SQL to support data-driven decision-making. Contribute to infrastructure-as-code and cloud engineering practices. Troubleshoot and improve production systems. Work with AI coding tools and model-backed product features. Mentor other engineers and contribute to engineering best practices. Work in an Extreme Programming environment with TDD, continuous deployment and fast feedback loops. Requirements: Strong commercial experience with Python. Experience building and running production services on AWS. Hands-on experience with AWS Lambda and DynamoDB. Experience with event-driven AWS services such as EventBridge and/or Step Functions. Strong understanding of typed Python and experience with Pydantic or similar approaches. Experience with Infrastructure as Code, preferably Terraform. Strong SQL and data modelling skills. Experience designing scalable backend systems and APIs. Strong understanding of software architecture and system design principles. Strong analytical and problem-solving skills. Experience working with AI coding tools in a professional engineering environment. Advanced English. Nice to have: Experience in FinTech, lending or credit. Experience with open banking data. Experience with Snowflake or similar data platforms. Experience with evolutionary architecture. Experience designing eventually consistent systems. Experience with domain-driven design. Experience with event-driven and serverless architectures. Experience working in regulated environments. Experience with GitHub Actions or similar CI/CD platforms. In return we offer: The friendliest community of like-minded IT-people Open knowledge-sharing environment – exclusive access to a rich pool of colleagues willing to share their endless insights into the broadest variety of modern technologies Mobilunity Medical Insurance program designed to attend our teams’ needs Paid vacations and sick leaves, including 5 paid days per year that don’t require a sick note Perfect office location in the city-center (900m from Lukyanivska metro station with a green and spacious neighborhood) or remote mode engagement: you can choose a convenient one for you, with a possibility to fit together both No open-spaces setup – separate rooms for every team’s comfort and multiple lounge and gaming zones English classes in 1-to-1 & group modes with elements of gamification Neverending fun: sports events, tournaments, music band, multiple affinity groups Come on board, and let’s grow together!