Software Engineer III ( JS/TS) at openx

Company at a Glance OpenX is focused on unleashing the full economic potential of digital media companies. We do this by making digital advertising markets and technologies that are designed to deliver optimal value to publishers and advertisers on every ad served across all screens. At OpenX, we have built a team that is uniquely experienced in designing and operating high-scale ad marketplaces, and we are constantly on the lookout for thoughtful, creative executors who are as fascinated as we are about finding new ways to apply a blend of market design, technical innovation, operational excellence, and empathetic partner service to the frontiers of digital advertising. About the role You will join the Core Exchange development team at OpenX. Our exchange handles billions of ad requests every day, connecting thousands of publishers with demand partners across the global advertising ecosystem. The platform runs in the cloud across multiple regions and operates at a scale where performance, reliability, correctness, and every millisecond matter. The role focuses on building tools and workflows that help users manage advertising transactions. These tools help users configure business rules, review transaction setup, and keep platform behavior aligned with business agreements and financial processes. This is a frontend-first engineering role with meaningful API ownership. Most of your work will focus on building high-quality user interfaces in TypeScript, primarily with React, while also contributing to Python-based APIs that support the product experience end-to-end. In practice, we expect the work to be roughly two-thirds frontend development and one-third API/backend development. Prior AdTech experience is helpful, but not required. Team setup You will join a cross-functional product engineering team with a dedicated Product Manager, Scrum Master, Engineering Manager, QA engineers, frontend and backend engineers, and regular collaboration with UX designers. This setup gives engineers direct access to product context and a real opportunity to influence both technical and user-facing decisions. What we offer: • Employment contract (17 708 - 19 792 PLN gross/monthly) OR B2B (147 - 164 PLN net/hourly) • Working with the newest technologies such as Cloud Computing (GCP) • Challenges at work that are difficult to find anywhere else! • Solving important problems in a scale • Joining a company that is growing and scaling • Flexible working hours & remote work option Key responsibilities: • Design and build high-quality, maintainable user interfaces using JavaScript/TypeScript and React. • Develop and maintain Python-based backend APIs that support frontend workflows and product capabilities. • Translate business rules, pricing logic, and data dependencies into intuitive user experiences and reliable API integrations. • Own features end-to-end, from requirements and technical design through implementation, testing, rollout, and operational quality. • Write and maintain automated tests as part of the development process, including frontend and API-level tests where appropriate. • Collaborate closely with Product, UX, QA, and Engineering to deliver reliable product experiences for enterprise users. • Improve the usability, reliability, and maintainability of existing systems. • Contribute to technical direction, code quality, and engineering practices within the team. Required Qualifications: • 4+ years of professional software engineering experience. • Experience building web applications with JavaScript or TypeScript. • Hands-on experience with React and modern frontend architecture. • Solid understanding of component-based development, state management, API integration, and frontend performance. • Experience designing and developing REST APIs or contributing to backend services, preferably in Python. • Practical understanding of databases and backend data flows. • Commitment to software quality, including writing automated tests where appropriate. • Strong ownership mindset and ability to collaborate effectively with Product, UX, QA, and Engineering. • Communicative Polish and English languages. Desired Characteristics: • Experience with advertising technology, marketing technology, digital media, marketplace platforms, financial workflows, or revenue-related systems. • Experience with GraphQL. • Experience with cloud-based systems such as Google Cloud Platform, AWS, or Azure. Technologies you will work with: • Frontend: TypeScript, React, single-page applications, React Testing Library. • API/backend: Python, REST APIs. • Testing: Playwright, pytest. • Data and infrastructure: PostgreSQL, Google Cloud Platform (GCP), Docker, Kubernetes, Terraform. • Delivery: CI/CD, Cloud Build, Spinnaker. • Tooling: modern AI-assisted development tools. • Collaboration: GitHub, code reviews, engineering communities of practice. Our benefits (on employment contract): • Annual performance bonus • Tax-deductible system due to copyright protection: 75% • Private health care for you and your family (covered by OpenX) • Private life and travel insurance • MultiKafeteria program • Training: access to the LinkedIn learning platform and Tech workshops • Holiday Allowance • Pension scheme (PPK from PZU) • Additional paid day off • Free parking lot • Access to peer to peer recognition platform • Monthly work-from-home allowance and one-time payment when you join us to help you set up your home office • We celebrate team members' important personal milestones (vouchers, gifts) OpenX VALUES Our five company values form a solid bedrock serving to define us as a group and guide the company. Our values remind us that how we do things often matters as much as what we do. WE ARE ONE We are one team. There are no exceptions. We are a group of strong and diverse individuals unified by a shared mission. We embrace challenges and win together as a team. We respect and care about our colleagues and cultivate an inclusive culture WE ARE CUSTOMER CENTRIC We innovate on behalf of our customers. We understand, respect, and listen carefully to our customers. We build great products to solve our customers’ problems. We manage our customers’ expectations clearly and honestly. We are a trusted partner to all of our customers - we act with integrity at all times. We care. OPENX IS OURS We are all owners of OpenX We all have a voice to improve OpenX We stake our personal and professional reputations on the excellence of our work We are not interested in just "doing our jobs"; we take ownership to drive results WE ARE AN OPEN BOOK We understand and respect what each of us does. We are eager to teach and share what we know with others, both internally and externally. We are eager to learn from others and we ask questions internally and externally.  WE EVOLVE FAST We take responsible risks and own and learn from our mistakes. We recognize and repeat success. We actively seek out and provide constructive feedback. We adapt quickly and embrace change. We tackle growth and learning with real urgency. We are endlessly curious. OpenX TRAITS Our three traits capture what makes a great team member at OpenX. HUMBLE Ideal team players are humble and demonstrate integrity. They put the team's success above their own, share credit generously, and value collective achievements. They are self-assured, open to coaching, and committed to continuous learning. DRIVEN Ideal team players are results-driven and motivated. They are curious, always seeking more to do, learn, and take on. As proactive problem-solvers, they take initiative without needing external motivation. They continuously think about the next steps and opportunities for improvement. SMART Ideal team players are smart and possess the intellectual acumen to understand the complexities of our organization and industry. They are interpersonally intelligent, good communicators, and exemplify sound judgment in their interactions across the company to foster a collaborative environment. OpenX is committed to equal employment opportunities. It is a fundamental principle at OpenX not to discriminate against employees or applicants for employment on any legally-recognized basis including, but not limited to: age, race, creed, color, religion, national origin, sexual orientation, sex, disability, predisposing genetic characteristics, genetic information, military or veteran status, marital status, gender identity/transgender status, pregnancy, childbirth or related medical condition, and other protected characteristic as established by law. 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