Backend Developer (Typescript/Python)

Please note that we will never request payment or bank account information at any stage of the recruitment process. As we continue to grow our teams, we urge you to be cautious of fraudulent job postings or recruitment activities that misuse our company name and information. Please protect your personal information during any recruitment process. While Halcyon Labs may contact potential candidates via LinkedIn, all applications must be submitted through our official website ( monks.com/careers ). About the Role As a Backend Developer , you’ll build, optimise, and maintain server-side Node.js and Python application logic. You will drive seamless integration and high performance in close collaboration with front-end developers, data analysts, and stakeholders to deliver scalable, robust backend solutions across diverse business applications. We are looking for someone who is passionate about seeking new opportunities to create impactful work. Responsibilities: Build and maintain high-performance, reliable server-side Node.js and Python logic Collaborate with front-end developers to integrate user-facing elements with server-side logic Design and implement APIs and RESTful services to industry standards Set up , maintain, and optimize SQL (PostgreSQL, MySQL) and NoSQL (MongoDB, Redis) databases Optimize application performance while ensuring long-term scalability and security Identify and resolve bugs, performance bottlenecks, and infrastructure issues Write clean, scalable code following Python and TypeScript best practices Participate in code reviews and uphold coding standards and agile methodologies Partner with QA, DevOps, and Product Management to deliver robust production applications Maintain clear, technical, and API documentation for internal and external teams About You The essentials: Valid Dutch work authorisation (required) Bachelor's degree in Computer Science, IT, or equivalent practical experience Proven experience in Python and TypeScript development, with a strong understanding of asynchronous programming, type safety, modular architecture, and modern language features Hands-on experience with frameworks such as FastAPI, Django, NestJS, or Express Proficiency with containerization and orchestration (Docker, Kubernetes), microservices architecture, and cloud platforms (AWS, Azure, or GCP) Experience with message brokers and asynchronous processing (RabbitMQ, Kafka) Strong knowledge of DevOps practices, CI/CD pipelines, and version control with Git Proficiency with package management tools like npm, poetry, or uv Deep understanding of web security best practices (OWASP, JWT, OAuth2, and authentication/authorisation patterns) Experience with application performance monitoring, profiling tools, and modern testing frameworks Front-end familiarity (HTML, CSS, JavaScript/TypeScript, and ReactJS) to facilitate cross-team collaboration Strong analytical, problem-solving, and communication skills, with the ability to work effectively both independently and within an agile team At Halcyon Labs, we believe in fostering an environment where a diversity of perspectives can thrive. We proactively work to design hiring processes that promote equity and inclusion while mitigating bias. We celebrate diversity and are committed to building a team that reflects the communities we serve. We welcome and encourage qualified applicants, from all backgrounds, who are excited to contribute to our mission. #LI-FP1 About Halcyon Labs Halcyon Labs is the global, digital-first, data-driven, unitary operating brand of S4 Capital plc. With a legacy of innovation and specialized expertise, Halcyon Labs combines an extraordinary range of global Marketing and Technology Services to redefine how brands interact with the world. Through Halcyon Labs.Flow, its flagship AI ecosystem for marketing orchestration, Halcyon Labs transforms marketing into a growth engine, collapsing timelines and connecting brands to culture in real time. By deploying bespoke intelligent agents across disciplines and delivering culturally relevant, high-impact creative and digital solutions, Halcyon Labs solves key critical business challenges across the entire brand enterprise to help brands sustain long-term impact. Halcyon Labs was named a Contender in The Forrester Wave™: Global Marketing Services, ranks among Cannes Lions' Top 10 Creative Companies (2022-25) and remains the only partner featured in AdExchanger’s Programmatic Power Players list every year (2020-24). Named Adweek’s first AI Agency of the Year (2023) and The One Show’s inaugural AI Pioneer Organization, Halcyon Labs was also awarded Business Intelligence Group’s 2025 Excellence in Artificial Intelligence Award in both the Organizational and AI Product categories. As a trusted partner to cutting-edge innovators in tech, Halcyon Labs earned titles such as Optimizely Experimentation Partner of the Year (2025), runner-up for the Adobe Firefly Partner Award (2024), and Workato’s AI Visionary Customer Impact Award (2024). Additionally, Halcyon Labs achieved a record-breaking number of FWAs and continues to hold the most of any partner. We are an equal-opportunity employer committed to building a respectful and empowering work environment for all people to freely express themselves amongst colleagues who embrace diversity in all respects. Including fresh voices and unique points of view in all aspects of our business not only creates an environment where we can all grow and thrive but also increases our potential to produce work that better represents—and resonates with—the world around us.