Blockchain is connecting the world to the future of finance. As the most trusted and fastest-growing global crypto company, it helps millions of people worldwide safely access cryptocurrency. Since its inception in 2011, Blockchain has earned the trust of over 90 million wallet holders and more than 40 million verified users, facilitating over $1 trillion in crypto transactions. As a Back-End Engineer on our Cryptocurrency Trading Platform, you will build the backend services that power our internal and external trading products — from order management and market data processing to the REST APIs and WebSocket streams that serve our web and mobile clients. You'll work closely with product, engineering, and trading teams, and contribute to our culture of engineering excellence. The role is based in London and the team is international. Responsibilities Design, build, and operate backend services in Kotlin and Python that power our trading products, from core trading workflows to client-facing APIs. Develop and improve services for order management, market data processing, and trade lifecycle handling in a real-time, high-volume environment. Build and maintain REST APIs and WebSocket streams that deliver real-time prices, order updates, and account data. Collaborate with cross-functional teams — product, frontend, trading — to adapt the platform quickly to new features and market conditions. Ensure high availability, reliability, and scalability of trading services, with a sharp focus on latency, observability, and testing. Contribute to architecture discussions and technical decisions, writing clean, maintainable code and sharing knowledge across the team. Requirements Professional experience building backend services, ideally in Kotlin and/or Python. Solid experience designing and building backend services and REST APIs; experience with WebSockets or other real-time streaming protocols such as NATS/JETSREAM is a plus. Working knowledge of SQL and experience integrating with multiple internal or third-party services. An understanding of performance fundamentals — identifying bottlenecks, managing latency, and building systems that stay responsive under load; experience with real-time or event-driven systems is a plus. Strong problem-solving skills and clear communication with both technical and non-technical colleagues. Curiosity and enthusiasm for learning new technologies; interest in financial markets or crypto is a plus, not a requirement. Familiarity with Docker/Kubernetes and cloud environments (AWS) is a plus. Compensation & Perks Full-time salary based on experience and meaningful equity in an industry-leading company Role based in our London office, with a mandatory in-office presence four days per week Work from Anywhere Policy - up to 20 days to work remotely ClassPass Budgets for learning & professional development Unlimited vacation policy; work hard and take time when you need it Apple equipment The opportunity to be a key player and build your career at a rapidly expanding, global technology company in an emerging field Flexible work culture Blockchain is committed to diversity and inclusion in the workplace and is proud to be an equal opportunity employer. We prohibit discrimination and harassment of any kind based on race, religion, color, national origin, gender, gender expression, sex, sexual orientation, age, marital status, veteran status, disability status or any other characteristic protected by law. This policy applies to all employment practices within our organization, including hiring, recruiting, promotion, termination, layoff, recall, leave of absence, and apprenticeship. Blockchain makes hiring decisions based solely on qualifications, merit, and business needs at the time. The personal data you provide will be used by Blockchain to process your application. To learn more about your rights, see our Applicant Privacy notice.
