Senior Software Engineer (TikTok)

We’re looking for a Senior Software Engineer to help build and evolve Smartly’s TikTok offering, enabling some of the world’s largest advertisers to manage and optimize their campaigns at scale. Working closely with TikTok and cross-functional teams at Smartly, you’ll develop new capabilities, strengthen integrations, and solve complex engineering challenges within our multi-channel advertising platform. This is a backend-heavy role focused on building reliable, high-performance services and APIs, with opportunities to contribute across the full stack and explore how AI and automation can improve our products and engineering practices. You’ll take ownership of significant product capabilities from concept to production, influencing technical architecture, product decisions, and how we build software. Your work will involve balancing user experience, scalability, reliability, and delivery speed while making a direct impact on customers. You’ll collaborate with experienced engineers, product managers, and designers to deliver meaningful solutions, while mentoring other engineers, sharing knowledge, and helping continuously improve our engineering practices. Our tech stack • Backend: Node.js, TypeScript • Frontend: React, TypeScript • Infrastructure: PostgreSQL, Redis, Kubernetes • Architecture: Distributed systems, event-driven services, large-scale data processing What you’ll do • Own significant TikTok product capabilities end-to-end, from customer-facing experiences to the backend services and APIs that power them • Contribute across the full stack, building customer-facing functionality and the backend services and APIs that support it, using Node.js, TypeScript, and React. • Drive technical and architectural decisions, balancing scalability, user experience, and delivery speed • Design, develop, and operate reliable, high-performance distributed systems at scale • Build and evolve reliable, scalable APIs and integrations between Smartly and TikTok, effectively managing API changes, rate limits, asynchronous operations, and platform constraints. • Develop and optimize data-intensive services using PostgreSQL and Redis, running on Kubernetes • Partner with product, design and other engineering teams to understand customer needs and shape solutions • Explore opportunities to leverage AI and automation to improve products and engineering workflows • Mentor fellow engineers, share knowledge, and contribute to high engineering standards and practices What we’re looking for • 6+ years of experience developing and operating production applications, ideally using TypeScript, Node.js, and React or similar technologies. • Experience delivering complex product capabilities end-to-end, from frontend development to backend architecture and API design. • Experience designing distributed systems and working with asynchronous, event-driven architectures at scale. • Experience building reliable systems and third-party API integrations that handle complex data flows and high volumes of data. • Ability to take ownership of complex technical challenges and drive them from concept to production. • Strong collaboration skills, with experience working closely with engineering, product, and design teams to shape solutions. • A pragmatic engineering mindset, making thoughtful trade-offs between product needs, technical quality, and delivery speed. • Interest in mentoring other engineers, sharing knowledge, and contributing to strong engineering practices. • Ability and willingness to work in a hybrid setup from our Helsinki office, 3 days per week What We Offer You At Smartly, we offer a place where you can advance your career. Here, you'll find: • An Inclusive Global Culture: Join a team of over 750 Smartlies, representing