Senior Backend Engineer – TikTok API Platform (Hybrid)

Smartly.io; Helsinki; Hybrid; EUR 90,000 - 130,000; Full time

Benefits offered by this job

Equity options

Flexible hybrid workplace

Healthcare packages

Paid holidays & family leave

Career development opportunities

Job summary

Smartly is seeking a Senior Software Engineer to help build and evolve the TikTok offering, enabling large advertisers to manage campaigns at scale. This backend-heavy role focuses on reliable services, APIs, and opportunities to work across the stack.

You'll own capabilities end-to-end, influence architecture, and mentor peers while balancing scalability, user experience, and delivery speed. The role is hybrid in Helsinki, with collaboration across product, design and engineering teams.

Qualifications

• 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 engineering, product, and design teams to shape solutions.
• A pragmatic engineering mindset, balancing product needs, technical quality, and delivery speed.
• Interest in mentoring other engineers and contributing to engineering practices.

Responsibilities

• Own significant TikTok product capabilities end-to-end, from customer-facing experiences to backend services and APIs.
• Contribute across the full stack, building customer-facing functionality and backend services using Node.js, TypeScript, and React.
• Drive technical and architectural decisions balancing scalability and user experience.
• Design, develop, and operate reliable, high-performance distributed systems at scale.
• Build and evolve APIs and integrations between Smartly and TikTok, managing API changes and platform constraints.
• Develop and optimize data-intensive services using PostgreSQL and Redis on Kubernetes.
• Collaborate 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 workflows.
• Mentor engineers, share knowledge, and promote high engineering standards.

Skills

Distributed systems

APIs

Team collaboration

Backend development

System design

Mentoring

Tools

Node.js

TypeScript

React

PostgreSQL

Redis

Kubernetes

Job description

Smartly is seeking a Senior Software Engineer to help build and evolve the TikTok offering, enabling large advertisers to manage campaigns at scale. This backend-heavy role focuses on reliable services, APIs, and opportunities to work across the stack.

You'll own capabilities end-to-end, influence architecture, and mentor peers while balancing scalability, user experience, and delivery speed. The role is hybrid in Helsinki, with collaboration across product, design and engineering teams.